##############################################################################
#                                                                            #
#                             CIF CORE DEFINITIONS                           #
#                             --------------------                           #
#                                                                            #
# This dictionary contains the names and definitions of the Core data items  #
# recognised by the International Union of Crystallography for the exchange  #
# of data between laboratories and submissions to journals and databases.    #
#                                                                            #
# The STAR/DDL dictionary is available as the file "ddl_core.dic"            #
# located at URL ftp://ftp.iucr.org/pub/ddl_core.dic                         #
#                                                                            #
# Copyright 2008 International Union of Crystallography                      #
##############################################################################


data_on_this_dictionary
    _dictionary_name            cif_core.dic
    _dictionary_version         2.4.1
    _dictionary_update          2010-06-29
    _dictionary_history
;
   1991-05-27  Created from CIF Dictionary text. SRH
   1991-05-30  Validated with CYCLOPS & CIF ms. SRH
   1991-06-03  Adjustments to some definitions. SRH
   1991-06-06  Adjustments a la B. McMahon. SRH
   1991-06-18  Additions & some redefinitions. SRH
   1991-07-04  Corrected 90:0 in *_detect_slit_. SRH
   1991-09-20  Additions & some redefinitions. SRH
   1991-09-20  Final published version. IUCr
   1991-11-12  Add _diffrn_ambient_environment. SRH
   1991-11-12  Allow 'c' for _atom_site_calc_flag. SRH
   1993-02-23  Apply global_ and 'unknown' -> '?' SRH
   1993-03-05  Changes resulting from MM dictionary. SRH
   1993-05-20  Changes arising from new DDL commands. SRH
   1993-08-05  Additional finetuning pre-Beijing. SRH
   1993-12-22  Introductory sections added to categories. BMcM
   1993-12-22  Additional categories from mm work: audit_author,
                 citation, atom_sites_fract_tran_matrix. BMcM
   1994-03-01  Add 'undef' to _refine_ls_hydrogen_treatment. BMcM
   1994-03-01  Add '_publ_section_exptl_prep' and '*_refinement'. BMcM
   1994-03-01  Add 'atom_site_aniso_ratio'. BMcM
   1994-04-15  Comments from IDB on draft version for circulation. BMcM
   1994-04-15  Added _publ_section_exptl_solution. BMcM
   1994-07-14  Added B. H. Toby's suggested _diffrn_radiation_xray_symbol
                 and _diffrn_radiation_xray_target. BMcM
   1994-08-05  Revised definition for _diffrn_reflns_number (S.R. Hall). BMcM
   1994-08-05  Added _atom_type_scat_length_neutron (B.H. Toby). BMcM
   1994-10-13  Reworded _diffrn_standards_ a la S.R. Hall. BMcM
   1994-10-13  Added _diffrn_radiation_probe for non-X-ray experiments. BMcM
   1995-01-17  Rewording of definition of _chemical_melting_point. BMcM
   1995-02-24  Changed text references to e.s.d to 'standard uncertainty'. BMcM
   1995-07-08  Added _chemical_formula_iupac. BMcM
   1995-07-09  Finally added _symmetry_equiv_pos_id. BMcM
   1995-07-09  _units_extension, _units_conversion and _units_description
                 superseded by _units and _units_detail. Suffixed datanames
                 retained as separate entries. BMcM
   1995-10-23  Added _refine_ls_R_Fsqd_factor and _refine_ls_R_I_factor BMcM
   1996-03-25  Correlated with mmCIF release 0.8 BMcM
   1996-05-16  Added some extra datanames for use by Acta:
                 _publ_section_synopsis, _publ_section_title_footnote,
                 _publ_author_footnote, _journal_paper_category, and various
                 _journal_index_ categories BMcM
   1996-05-20  Added geom_hbond category BMcM
   1996-06-10  Datanames with suffixes to indicate units moved to a new
                 compatibility dictionary cif_compat.dic BMcM
   1996-06-10  Embarrassing _units_ stuff removed from geom_hbond BMcM
   1996-06-10  _list_mandatory and _list_reference added to _publ_author_
                 datanames (where _list was given as "both") BMcM
   1996-06-10  Added audit_conform category BMcM
   1996-06-11  Added audit_link category BMcM
   1996-06-11  Reworded _exptl_crystal_F_000 definition BMcM
   1996-06-11  Added _atom_site_U_equiv_geom BMcM
   1996-06-11  Added publ_body category BMcM
   1996-06-27  Added examples for most of the remaining category overviews
                 BMcM
   1996-06-27  Added _journal_language BMcM
   1996-06-28  Added area-detector definitions from mmCIF dictionary:
                 _diffrn_measurement_device_details, *_specific and *_type;
                 _diffrn_radiation_detector_details, *_specific, *_type;
                 _diffrn_radiation_source_details, *_power, *_specific,
                 *_target, *_type; reflns_shell category  BMcM
               Added _refine_ls_d_res_high and *_low and changed wording of
                 definitions for R factors to include these. BMcM
               Added 'h' and 'f' flags to _refln_observed_status. BMcM
   1996-07-05  Some typos fixed and examples modified as suggested by
                 P.Strickland and I.D.Brown. BMcM
   1996-07-27  BMcM:
               Added example for _diffrn_orient_refln_[] from G. Madariaga
               U~ij~ changed to U^ij^ a la Nomenclature Commission
               Definition of _diffrn_ambient_environment changed to omit vacuum
                 as a possible default environment
               Changed definitions of *_site_symmetry_* items to I.D.Brown's
                 suggested wording.
               Compressed various journal indexing categories into one
               Changed upper enumeration values for _refln_symmetry_epsilon
                 and _refln_symmetry_multiplicity to 48.
               Added references to deprecated use of B values.
               Modified descriptions of phone, fax number conventions
               _publ_manuscript_incl_ entries reworded for greater
                 clarity and given individual data blocks
               Added _list_reference to _symmetry_equiv_pos_id and changed
                 _list value to 'both' for *_as_xyz to allow the P1 case
               Added _atom_site_B_equiv_geom for completeness
               Modified definitions of _atom_sites_[Cartn,fract]_tran_vector_
               Added _units stuff to _chemical_formula_weight_* and
                 _exptl_crystal_density_ items
               Added *_theta, *_omega to _diffrn_orient_refln_angle_
               Added 'q' to enumeration list for _diffrn_refln_scan_mode
               Reworded definition in _diffrn_scale_group_[]
               Permitted esd for _refln_phase_meas (necessitates splitting
                 _refln_phase_ datablock in two)
               Added _type_conditions esd for _reflns_scale_meas_
   1996-07-28  BMcM:
               Added example for refln_scale_[] and second example for
                 _refln_[] from Xtal test data set.
               Changed references to category names to CAPITALS.
               Merged CELL and CELL_MEASUREMENT categories.
               Added _units deg to all angle quantities.
               Renamed _citation_journal_coden_CAS as
                 _citation_journal_abstract_id_CAS
               Removed _diffrn_measurement_device_details, *_specific,
                 *_type, _diffrn_radiation_detector_details, *_specific,
                 *_type, _diffrn_radiation_source_power, *_specific,
                 *_target, *_type, pending full analysis of requirements
                 for describing diffraction apparatus.
               Reworded _exptl_crystal_F_000 definition again
   1996-08-03  Reworded _refine_ls_number_reflns definition a la S.R.Hall BMcM
   1996-09-10  BMcM:
               Clarified _diffrn_attenuator_scale definition with help from SRH
               In _refln_symmetry_multiplicity, changed 'structure-factor
                 value' to 'structure-factor magnitudes'
               Slight modification to _diffrn_reflns_number to exclude all
                 systematic absences, not just those due to centring
               Removed footnote markers from example of
                 _publ_section_title_footnote
               Added new example to SYMMETRY_EQUIV category to explain the
                 use of _symmetry_equiv_pos_id
               Reworking of DIFFRN_RADIATION and DIFFRN_MEASUREMENT
                 categories and introduction of DIFFRN_DETECTOR and
                 DIFFRN_SOURCE a la I.D.Brown
   1996-09-11  Corrected category assignment for _diffrn_standards_ items BMcM
   1996-09-12  BMcM:
               Added _cell_id and _cell_measurement_refln_id
               Changed the term "id" to "identifier" in definitions
               Renamed _citation_journal_abstract_id_CAS as
                 _citation_abstract_id_CAS
               Added _audit_block_code and changed definition of
                  _audit_link_block_code to refer to it
   1996-09-18  BMcM:
               Fine tuning of IDB's new DIFFRN categories: in DIFFRN_DETECTOR
                 changed *_type to *_device and added *_device_type. Moved
                 _diffrn_radiation_detector back to DIFFRN_RADIATION category
                 with expanded definition. Reworded definitions of
                 _diffrn_measurement_device and *_device_type. In
                 DIFFRN_RADIATION changed enumeration range for
                 *_polarisn_norm to -180:180 and added 'as viewed from the
                 specimen' to the definition; also added 'Cu K-L~2,3~' to
                 examples for *_type. Reworded definitions for
                 _diffrn_refln_index and _diffrn_source_target, and changed
                 _type of _diffrn_source_power to "numb".
               Introduced _diffrn_detector_dtime in the DIFFRN_DETECTOR
                 category and restored _diffrn_radiation_detector_dtime to
                 DIFFRN_RADIATION
   1996-09-25  BMcM:
               Reworded definitions of _atom_site_disorder_assembly and *_group
   1996-10-02  BMcM:
               Changed _symmetry_equiv_pos_id to _symmetry_equiv_pos_site_id
                 in recognition of the technical meaning of 'position' in
                 International Tables
               Addition of the names of the relevant units to definitions of
                 _atom_type_scat_length_neutron, _exptl_crystal_size_,
                 _geom_hbond_distance_, _refine_ls_d_res_high and *_low,
                 _reflns_shell_d_res_high and *_low; and cosmetic expansion
                 of units listed in the definitions for _diffrn_source_current,
                 *_power and *_voltage
               Addition of '_related_function conversion' to
                 _atom_site_B_equiv_geom and *_U_equiv_geom and
                 _atom_site_B_iso_or_equiv and *_U_iso_or_equiv
               Examples for CELL_MEASUREMENT_REFLN and DIFFRN_REFLN from
                 Gotzon Madariaga
               Renamed _atom_site_U_equiv_geom as _atom_site_U_equiv_geom_mean
                 and likewise for *_B_* to increase the consistency of
                 abbreviations, as suggested by I.D. Brown
               Added disorder example to the ATOM_SITE category description
   1996-10-15  BMcM:
               Modified description of example for DIFFRN_REFLN
               Changed _enumeration_range of _atom_site_attached_hydrogens
                 from 0:4 to 0:8 (cf CSD entry with refcode DUTMAG01) (PRE)
               Added '_enumeration_default cif' to _publ_body_format
               Changed underscores to spaces in the example for the Hall
                 spacegroup symbol in data_symmetry_[]
               Deleted extraneous '_' in data_(_)citation_abstract_id_CAS
   1996-10-27  BMcM: Changed psiscan to psi-scan at request of SRH
   1996-11-05  BMcM:
               Changed _citation_book_coden_ISBN to _citation_book_id_ISBN,
                 _citation_journal_coden_ASTM to _citation_journal_id_ASTM,
                 _citation_journal_coden_CSD to _citation_journal_id_CSD,
                 _citation_journal_coden_ISSN to _citation_journal_id_ISSN,
                 and _citation_Medline_AN to _citation_database_id_Medline.
                 Also modified description of CODEN in _citation_journal_id_ASTM
                 and _database_journal_ASTM (suggested by PMDF)
               The phrase 'diffraction data' modified to 'intensities' in
                 several places, some other cosmetic commas and enforcement
                 of consistent lower-case units names (PMDF)
               Clarification of the definition for
                 _diffrn_radiation_polarisn_norm (PMDF)
               Added 'constr' to _refine_ls_hydrogen_treatment (SRH)
               Corrected misassignment of category of
                 _diffrn_radiation_detector_dtime (H.J.Bernstein)
   1996-11-06  BMcM:
               Added "_list   yes" to items in the REFLNS_SHELL category (IDB)
               Added "measured" to definition of _reflns_shell_number_unique_all
               Changed enumeration range for _diffrn_standards_decay_% to
                 ":100" and added statement about negative values (PMDF/SRH)
   1996-11-08  BMcM:
               _diffrn_radiation_detector, _diffrn_radiation_detector_dtime and
                 _diffrn_radiation_source removed (these will be transferred to
                 cif_compat.dic for compatibility with files conforming to the
                 original dictionary)
               _diffrn_radiation_wavelength_* items moved to new category
   1996-11-12  BMcM:
               Deleted _cell_id and _cell_measurement_refln_id, and
                 clarified the intent of the CELL category in _cell_[] (PMDF)
               Some small rewordings of various _diffrn_* items due to
                 B.H.Toby
   1996-11-14  BMcM:
               Imposed consistency on the nomenclature of diffraction device
                 data names: _diffrn_detector_device_type -> *_detector_type,
                 _diffrn_measurement_device_details -> *_measurement_details,
                 *_measurement_device_type -> *_measurement_type; introduction
                 of _diffrn_source_device and parallel definitions. Existing
                 *_measurement_details example moved to *_special_details (PMDF)
   1996-11-21  BMcM:
               Reintroduced _diffrn_measurement_device_details, further tidying
                 of data names thus: _diffrn_measurement_type -> *_device_type;
                 _diffrn_detector_device and _diffrn_source_device both drop
                 "_device" (PMDF)
               Added _journal_data_validation_number and
                 _publ_requested_category to enable handling of CIF-access
                 submissions by Acta Cryst. C
   1996-11-23  A few typos fixed. BMcM
   1996-11-24  BMcM:
               Added 'gaussian', 'multi-scan' and 'numerical' to enumeration
                 list for _exptl_absorpt_correction_type (SRH)
               Added 'mixed' to enumeration list for
                 _refine_ls_hydrogen_treatment (SRH)
   1996-11-25  A few typos fixed (BMcM)
   1996-11-27  BMcM:
               Removed looped _related_item from _publ_contact_author and
                 reintroduced _diffrn_radiation_detector, *_dtime and
                 _diffrn_radiation_source (see 1996-11-08) with
                 "_related_function replace" as a preparation for
                 using this mechanism further in version 2.1.
   1996-11-27  Release version 2.0. IUCr
   1997-01-20  BMcM:
               Some small changes thanks to PMDF. Double space after period
                 at end of sentence changed to single space throughout;
                 _citation_database_id_Medline _diffrn_detector_type moved
                 to correct alphabetic sequence; space introduced between
                 sentences in definition of _citation_journal_id_CSD; some
                 other minor grammatical changes
   1997-10-30  BMcM: (changes to align with Acta C Notes for Authors)
               Obsoleted *_obs_* entries in REFLNS and REFINE_LS categories
                 and replaced with *_gt_*; obsoleted _refine_ls_shift/esd_
                 by _refine_ls_shift/su_; obsoleted
                 _atom_site_thermal_displace_type by *_adp_type
   1997-11-05  BMcM: (changes to align with Acta C Notes for Authors)
               Added _diffrn_detector_area_resol_mean,
                 _diffrn_measured_fraction_theta_max and *_full,
                 _diffrn_reflns_theta_full
   1997-11-05  BMcM: Added _reflns_number_Friedel; changed various *_obs
                 items in examples to *_gt equivalents and likewise for
                 other obsoleted items
   1997-11-24  BMcM: Slightly changed wording of _reflns_number_Friedel and
                 _reflns_threshold_expression at suggestion of I.D.Brown.
                 Modified definition of _refine_ls_abs_structure_Flack and
                 changed the text of the example in category REFINE at
                 the request of H.D.Flack.
   1997-12-08  BMcM: Removed the phrase "(enantiomorph or polarity)" from
                 _refine_ls_abs_structure_Flack and *_Rogers because
                 "absolute structure" is a phrase uniquely defined (H.D.Flack)
   1997-12-08  BMcM: Several instances of \s changed to u
   1997-12-08  BMcM: Modified definitions of _reflns_number_total and
                 *_Friedel (after H.D.Flack) to clarify the distinction between
                 crystal-class and Laue-symmetry independent reflection sets
   1997-12-08  BMcM: Added _chemical_absolute_configuration and
                  _chemical_optical_rotation (H.D.Flack)
   1998-08-04  BMcM: Moved _diffrn_pressure_history and _diffrn_thermal_history
                  from draft msCIF dictionary to core as
                  _exptl_crystal_pressure_history and
                  _exptl_crystal_thermal_history (G. Madariaga/I.D.Brown)
                    Moved _diffrn_symmetry_description and REFINE_LS_CLASS
                  from draft msCIF dictionary to core (G. Madariaga/I.D.Brown)
   1998-08-04  BMcM: Minor rewordings of _refine_ls_R_Fsqd_factor,
                  _refine_ls_R_I_factor, various definitions referring to
                  F_calc in electrons, and _reflns_shell_number_unique_*
                  (I.D.Brown)
   1998-08-04  BMcM: added _reflns_Friedel_coverage (H.D.Flack/S.R.Hall)
   1998-08-04  BMcM: changed formula for F(000) (from
                  F(000) = [ sum (f~r~^2^ + f~i~^2^) ]^1/2^     to
                  F(000) = [ (sum f~r~)^2^ + (sum f~i~)^2^ ]^1/2^ ) (H.D.Flack)
   1998-08-04  BMcM: added 'syn' and 'unk' as enumerations to
                  _chemical_absolute_configuration (H.D.Flack/A.Linden)
   1998-09-02  BMcM: added _exptl_crystal_size_length and modified slightly
                  the definition of _exptl_crystal_size_ (W.Clegg/I.D.Brown)
                    Added _diffrn_attenuator_material (I.D.Brown)
                    Added sentence explaining the physical meaning of the
                  _enumeration_range to _refine_ls_abs_structure_Flack
                  (H.D.Flack)
                    Some rewording in _chemical_absolute_configuration implying
                  that for absolute configuration determination the measurement
                  and reporting of the optical rotation in solution are
                  considered mandatory. (H.D.Flack)
                    Some rewording in _reflns_number_total and *_gt to clarify
                  the inclusion of Friedel reflections; addition of
                  _reflns_Friedel_coverage; deletion of _reflns_number_Friedel
                  (H.D.Flack/S.R.Hall)
                    Further minor rewording to _reflns_shell_number_unique_all,
                  *_gt, *_obs (H.D.Flack)
   1998-09-10  BMcM: transferred _diffrn_reflns_number_of_classes and the
                  categories DIFFRN_REFLNS_CLASS, REFLNS_CLASS and
                  REFLNS_SHELL_CLASS from the draft msCIF dictionary; added
                  _diffrn_refln_class_code and _refln_class_code to link
                  individual reflections to their related categories.
   1998-12-08  BMcM: implemented H.D. Flack's reworking of DIFFRN_REFLNS_CLASS,
                  REFLNS_CLASS, REFLNS_SHELL_CLASS and REFINE_LS_CLASS, deleting
                  the latter two; removed _diffrn_reflns_number_of_classes.
   1998-12-15  BMcM: completed the above reworking; fixed embarrassing typo for
                  _related_function
   1999-01-16  BMcM: coreDMG review of version 2.1beta5. Numerous small changes
                  from I.D.Brown, the most significant being:
                   _atom_site_occupancy definition clarifies how to impose an
                    experimental uncertainty on the _enumeration_range;
                   _atom_site_U_iso_or_equiv enumeration range set to infinity;
                   _atom_type_analytical_mass_% enumeration range set as 0:100;
                   expanded definitions of _diffrn_radiation_probe and *_type to
                    clarify the distinction between these two items;
                   added reference to _exptl_crystal_size to the definition of
                    _exptl_crystal_description, and modified the definition of
                    _exptl_crystal_face_diffr_ ;
                   new data item _refln_d_spacing;
                   clarified the role of _reflns_special_details in specifying
                    whether Friedel pairs have been averaged;
                  Numerous small changes from H.D.Flack, most significantly:
                   removed enumeration range from _diffrn_refln_counts_ because
                    *_net can go negative;
                   fixed various typos in equations for wR and S;
                   removed reference to Friedel reflections from
                    _refln_symmetry_multiplicity
   1999-01-24  BMcM: further revision to wording of _refln_symmetry_multiplicity
                   following discussions by HDF and IDB
                  Numerous small changes from G.Madariaga, most significantly:
                   a instead of A for real-space cell lengths
                    (_atom_site_B_iso_or_equiv and _atom_site_U_iso_or_equiv);
                   _related_function alternate for _atom_site_Cartn_ & _fract_;
                   "or scattering lengths" added to _atom_type_scat_source;
                   deleted incorrect _list_reference in DIFFRN_RADIATION;
                   added rtf to enumeration in _publ_body_format;
                   added enumeration range to _refine_ls_abs_structure_Rogers
   1999-02-04  BMcM: fixed some long lines
   1999-02-06  BMcM: data names using sigma as an indicator of experimental
                     standard uncertainty replaced by equivalents using the
                     preferred 'u' notation (HDF):
                          _diffrn_refln_intensity_sigma
                          _diffrn_reflns_av_sigmaI/netI
                          _diffrn_reflns_class_av_sgI/I
                          _diffrn_standards_scale_sigma
                          _reflns_shell_meanI_over_sigI_all
                          _reflns_shell_meanI_over_sigI_gt
                 (_reflns_shell_meanI_over_sigI_obs already replaced by *_gt)
                   addition of '_related function alternate' to new data
                     items corresponding to old items with
                     '_related_function replace' (SRH)
                   Example for _citation_journal_id_CSD changed to 0070 to
                     reflect current practice at PDB (F.C.Bernstein)
                   Added _atom_type_scat_dispersion_source (GM)
   1999-03-24  Some minor cosmetic modifications (BMcM)
   1999-03-24  Release version 2.1. IUCr
   2001-01-09  BMcM: simplified entry for _chemical_absolute_configuration
                     (H.D.Flack)
                     Added _geom_bond_valence and the new categories
                     VALENCE_PARAM and VALENCE_REF (I.D.Brown)
   2001-01-11  BMcM: Categories EI, EO, EM added to _publ_requested_category
   2001-01-11  Release version 2.2. IUCr
   2003-09-28  BMcM: incorporated changes approved by COMCIFS following
                     discussions of the core Dictionary Management Group:
               _atom_site_fract_ nonsense enumeration default value removed
               _atom_site_refinement_flags deprecated in favour of new
                     *_flags_posn, *_adp and *_occupancy items
               _atom_sites_special_details added
               _cell_reciprocal_angle_ and *_length_ added
               '_type_conditions esd' added to _chemical_melting_point
               _chemical_melting_point_gt and *_lt added
               Added several new items describing chemical properties to
                     the CHEMICAL category: _chemical_properties_biological and
                     *_physical, _chemical_temperature_decomposition_* and
                     *_sublimation_*, at the request of CCDC
               _citation_database_id_CSD added at request of CCDC
               Several additional tags storing deposition numbers of
                     database entries and record revision history at
                     request of CCDC: _database_code_depnum_ccdc_fiz,
                     *_journal, *_archive and _database_CSD_history
               Added _diffrn_ambient_pressure_gt,lt and *_temperature_gt,lt
               Added _diffrn_source_take-off_angle
               Added _diffrn_standards_decay_%_lt
               _diffrn_reflns_measured_fraction_resolution_full and *_max
                     introduced as replacements for
                     _diffrn_measured_fraction_theta_full and *_max, moved
                     to a more appropriate category and defined in terms
                     of resolution rather than angle which depends on the
                     radiation used.
               Likewise for _diffrn_reflns_resolution_full and *_max as
                     replacements for _diffrn_reflns_theta_full and *_max
               More specific parsable tags for crystal colour introduced as
                     _exptl_crystal_colour_primary, *_modifier and *_lustre
               Added _exptl_crystal_density_meas_gt,lt and *_meas_temp_gt,lt
               Added _exptl_crystal_recrystallization_method
               Added _publ_contact_author_id_iucr and _publ_author_id_iucr
                     to allow unique author identification by IUCr database
                     reference identifier
               More datanames for recording imprecise quantities:
                     _refine_ls_shift/su_max_lt and _refine_ls_shift/su_mean_lt
               Added the categories SPACE_GROUP and SPACE_GROUP_SYMOP
                     as imports from the symmetry dictionary cif_sym.dic
               Added _related_function 'replace' to a number of items in
                     the old SYMMETRY category pointing to the preferred
                     items from the new SPACE_GROUP category
   2003-08-19  BMcM: formal approval for COMCIFS for the additions and
                     contingent changes discussed on the coreDMG discussion
                     list from June 2002
   2003-09-29  BMcM: second round of changes from coreDMG discussions:
               Added _enumeration_range to new _chemical_temperature_* items;
               Expanded definition of _space_group_symop_operation_xyz to
                     make explicit the need for inclusion of centring
                     translations (HDF/IDB)
               Removed _diffrn_reflns_measured_fraction_resolution_full and
                     *_max for reconsideration following suggestion by
                     Curt Haltiwanger that terms are needed that do not
                     refer to resolution or theta
               Likewise removed _diffrn_standards_decay_%_lt for further
                     consideration, and added _type_conditions esd to
                     _diffrn_standards_decay_% as a measurable quantity
                     (CH/HDF)
               Modified _example_detail for _space_group_symop_operation_xyz
                     to use a full and unambiguous wording in accordance
                     with International Tables A (CH/IDB/HDF)
   2003-09-29  Removed "_type_conditions esd" from the remaining *_gt and
                     *_lt items at the suggestion of Gotzon Madariaga:
                     since these are ceiling/floor values a measurable
                     uncertainty is pointless (BMcM)
   2003-10-01  Fixed some typos following checking by IDB (BMcM)
   2003-10-03  BMcM: Final editorial pass. Added _related_function alternate
                     to _exptl_crystal_colour. Also added this flag to the
                     new items which replace existing ones:
                     _atom_site_refinement_flags_* and the _space_group_ items
   2003-10-04  Release version 2.3. IUCr
   2004-06-06  BMcM: minor editorial changes for International Tables Volume G.
                     Text of _atom_sites_*_tran_* definitions changed to
                     ATOM_SITE from STOM_SITES.
                       Some realignment of examples to fit column width.
   2004-09-11  BMcM: corrected related item error in
                     _atom_site_refinement_flags_posn, *_adp and *_occupancy
   2004-11-26  NJA: updated reference to IT Vol A from 1987 to 2002
   2004-12-22  NJA: minor corrections to hyphenation, spelling and punctuation
                    atom_site definition: ', and so on' removed
                    _atom_site_aniso_B_: 1/4 in formula replaced by (1/4)
                    _atom_site_aniso_label: '...atom coordinate list' changed
                     to '...atom in the atom coordinate list'
                    _atom_site_B_iso_or_equiv: 'anisotropic temperature factor
                      parameters' changed to 'anisotropic displacement
                      components'
                    _atom_site_label: 'Each label may have...' changed to
                      'Different labels may have...'
                    _atom_site_type_symbol: '...atom specie(s)...' changed to
                      'atom species (singular or plural)...'
                    _atom_type_scat_Cromer_Mann_: reference to Volume C
                      updated to 2004
                    _atom_type_symbol: 'atom specie(s)' changed to
                      'atom species (singular or plural)'
                    _audit_conform_dict_location: 'where the conformant
                      dictionary resides' changed to 'for the dictionary
                      to which the current data block conforms'
                    _audit_conform_dict_version: 'conformant dictionary'
                      changed to 'dictionary to which the current data
                      block conforms'
   2004-12-23  NJA: minor corrections to hyphenation, spelling and punctuation
                   _audit_contact_author_fax,_audit_contact_author_phone:
                      edited slightly
                   _cell_angle_: 'in degrees of the reported structure'
                      changed to 'of the reported structure in degrees'
                   _cell_measurement_pressure: 'pressure used to synthesize
                      the sample' changed to 'pressure at which the sample
                      was synthesized'
                   _cell_measurement_theta_: 'angles in degrees of reflections
                      used to measure the unit cell' changed to 'angles
                      of reflections used to measure the unit cell in degrees'
                   _cell_reciprocal_angle_: 'angles in degrees defining
                      the reciprocal cell' changed to 'angles defining
                      the reciprocal cell in degrees'
                   _chemical_[]: 'compounds' changed to 'compound'
                   _chemical_optical_rotation: 'c is the value of CONC in g'
                      changed to 'c is the value of CONC as defined above'.
                   _chemical_properties_physical, _biological: 'free
                      description' changed to 'free-text description'
                   _chemical_conn_atom_display_: 'if absent...staff.' deleted
                   _citation_[]: 'literature cited relevant' changed to
                      'literature cited as being relevant'
                   _citation_*: 'book chapters' changed to 'books or
                      book chapters'
                   _citation_country: 'both journal articles and' deleted
                   _citation_database_id_CSD: 'containing' changed to
                      'that contains'
                   _citation_language: 'citation appears' changed to
                      'cited article is written'
                   _diffrn_crystal_treatment: 'intensity measurement' changed
                      to 'the intensity measurements'
                   _diffrn_special_details: 'diffraction measurement' changed
                      to 'intensity-measurement'
                   _diffrn_attenuator_scale: 'This scale must be multiplied
                      by the measured intensity to convert it...' changed
                      to 'The measured intensity must be multiplied by
                      this scale to convert it...'
                   _diffrn_orient_matrix_[]: 'used in data measurement'
                      changed to 'used in the measurement of the
                      diffraction intensities'
                   _diffrn_orient_refln_angle_: 'in degrees of a reflection...
                      matrix' changed to 'of a reflection...matrix in degrees'
                   _diffrn_radiation_probe,_diffrn_radiation_type:
                      definitions reworded slightly
                _diffrn_refln_angle_: 'in degrees of a reflection' changed
                   to 'of a reflection in degrees'
                _diffrn_refln_elapsed_time: 'diffraction measurement'
                   changed to 'the diffraction experiment'
                _diffrn_refln_scale_group_code: 'applying' changed to
                   'applicable'
                _diffrn_refln_scan_mode: 'with a diffractometer' changed to
                   'for measurements using a diffractometer'
                _diffrn_refln_scan_rate: 'to measure the intensity in
                   degrees per minute' changed to 'in degrees per minute
                   to measure the intensity'
                _diffrn_refln_standard_code: 'identifying' changed to
                  'indicating'; 'intensity' changed to 'reflection'
                _diffrn_reflns_class_d_res_high,_low: defintions rephrased.
                _diffrn_source_details: 'used' deleted.
                _diffrn_source_target: 'for generation of' changed to
                   'to generate'
                _diffrn_standards_decay_%: 'at the start of the measurement
                   process and at the finish' changed to 'from the start of
                   the measurement process to the end'
                _diffrn_standards_number: 'used in the diffraction
                   measurements' changed to 'used during the measurement of
                   the diffraction intensities'
                _exptl_absorpt_correction_type: 'no more detailed
                   information is' changed to 'more detailed information
                   is not'.
                _exptl_crystal_[]: 'and so on' deleted
                _exptl_crystal_face_perp_dist: 'millimetres of the face'
                   changed to 'millimetres from the face'
                _geom_[], _geom_angle_[], _geom_bond_[], _geom_contact_[],
                _geom_hbond_[], _geom_torsion_[]: 'contents of the' deleted
                _geom_contact_[], _geom_torsion_[]: year for reference for
                   example 1 corrected from 1991 to 1992
                _geom_hbond_angle_DHA: 'Site at *_D' changed to  'Site at *_H'
                _publ_contact_author_fax: definition rephrased slightly
                _publ_requested_category: Cif-access codes marked as '(no
                longer in use)'

   2005-01-05  NJA: minor corrections to hyphenation, spelling and punctuation
                   _refine_ls_*: 'least squares' changed to 'least-squares
                      refinement'
                   _refine_ls_restrained_S_all: `Y(calc)  = the observed
                      coefficients` changed to `Y(calc)  = the calculated
                      coefficients`
                   _refine_ls_restrained_S_gt: `Y(calc)  = the observed
                      coefficients` changed to `Y(calc)  = the calculated
                      coefficients`
                   _refine_ls_restrained_S_obs: `Y(calc)  = the observed
                      coefficients` changed to `Y(calc)  = the calculated
                      coefficients`
                   _refine_ls_shift/esd_*: 'divided by' changed to 'to'
                   _refine_ls_shift/su_*: 'divided by' changed to 'to'
                   _refine_ls_class_d_res_*: edited slightly
                   _refine_ls_d_res_*: edited slightly
                   _refln_intensity_*: edited slightly
                   _refln_symmetry_multiplicity: reference to Volume A updated
                      to (2002), Chapter 10.1
                   _reflns_d_resolution_*: edited slightly
                   _reflns_class_d_res_*: edited slightly
                   _reflns_shell_d_res_*: edited slightly
                   _space_group_name_Hall: erratum added to reference to Hall
                      (1981); reference to Volume B updated to 2001.
                   _space_group_name_H-M_alt: reference to Volume A updated
                      to (2002)
                   _symmetry_Int_Tables_number: reference to Volume A updated
                      to (2002)
                   _symmetry_space_group_name_Hall: erratum added to reference
                      to Hall (1981)
                   _symmetry_space_group_name_H-M: reference to Volume A
                      updated to (2002)
                   _symmetry_equiv_pos_as_xyz: reference to Volume A updated
                      to (2002)
   2005-01-11  NJA: more minor corrections to hyphenation, spelling and
                     punctuation
   2005-01-21 NJA: _reflns_shell_Rmerge_I_obs: related item changed from
                       _reflns_shell_Rmerge_I_obs to _reflns_shell_Rmerge_I_gt
   2005-06-21 NJA: corrections to proofs of Intl Tables G Chapter 4.1 included.
                    New data name _publ_author_email added.
   2005-06-27 BMcM: Removed _list_mandatory yes from _atom_site_aniso_label
                    in response to cif-developers list discussion 
   2007-03-27 BMcM: Added _publ_section_related_literature; added
                    new categories (QI, QM, QO) to _publ_requested_category
   2007-12-04 BMcM: Fixed typo in equation appearing in
                    _diffrn_reflns_av_sigmaI/netI and
                    _diffrn_reflns_av_unetI/netI
   2007-12-04  IDB: Added new items approved by coreDMG:
                    SUMMARY

                    1.  _atom_sites_solution_
                        Added new flags notdet, dual, other (Bruce Noll)

                    2.  _chemical_enantioexcess_
                        Added items *_bulk, *_bulk_technique, *_crystal,
                        *_crystal_technique (H. D. Flack)

                    3.  _diffrn_..._measured_fraction_
                        Added sentences to definitions of
                        _diffrn_reflns_resolution_full, *_theta_max and
                        *_resolution_max. Added new data items
                        _diffrn_reflns_Laue_measured_fraction_full, *_max
                        _diffrn_reflns_point_group_measured_fraction_full
                        and *_max

                    4.  _diffrn_standards_decay_%
                        Clarified definition and added examples.

                    5.  _distributed_density_
                        Added _atom_site_distributed_density_id and the new
                        DISTRIBUTED_DENSITY category following suggestions
                        from David Watkin.

                    6.  _exptl_absorpt_correction_T_max, *_T_min
                        Clarified definition and added items
                        _exptl_transmission_factor_max and *_min

                    7.  _geom_bond_multiplicity
                        New data item added.

                    8.  _publ_section_keywords
                        New data name added.

                    9.  _refine_ls_F_calc
                        Added _refine_ls_F_calc_details, *_formula and
                        *_precision.

                    10. _symmetry_equiv
                        Added _enumeration_default 1 to _space_group_symop_id
                        and _symmetry_equiv_pos_site_id; added
                        _enumeration_default x,y,z to
                        _symmetry_equiv_pos_as_xyz; added comment about the
                        need to have the identity as symop 1 to
                        _space_group_symop_operation_xyz, _space_group_symop_id,
                        _symmetry_equiv_pos_as_xyz and
                        _symmetry_equiv_pos_site_id
   2008-02-10 BMcM: Final changes after COMCIFS review:
                        Alphabetization of _atom_sites_Cartn_transform_axes,
                        _citation_journal_full and a few others
                        Removed upper enumeration limit from
                        _diffrn_reflns_Laue_measured_fraction_full
                        Fixed typo in definition of _distributed_density_[].
                        Added comments from GM, IDB, RWGK querying aspects
                        of some other definitions in the proposed
                        DISTRIBUTED_DENSITY category.
                        Removed DISTRIBUTED_DENSITY category for further review.
                        Also removed data_atom_site_distributed_density_id
   2010-06-29 BMcM: Added _diffrn_radiation_wavelength_determination
;

###############
## ATOM_SITE ##
###############

data_atom_site_[]
    _name                      '_atom_site_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _atom_site_label
    _atom_site_fract_x
    _atom_site_fract_y
    _atom_site_fract_z
    _atom_site_U_iso_or_equiv
    _atom_site_adp_type
    _atom_site_calc_flag
    _atom_site_calc_attached_atom
      O1   .4154(4)  .5699(1)  .3026(0)  .060(1)  Uani  ?    ?
      C2   .5630(5)  .5087(2)  .3246(1)  .060(2)  Uani  ?    ?
      C3   .5350(5)  .4920(2)  .3997(1)  .048(1)  Uani  ?    ?
      N4   .3570(3)  .5558(1)  .4167(0)  .039(1)  Uani  ?    ?
      C5   .3000(5)  .6122(2)  .3581(1)  .045(1)  Uani  ?    ?
      O21  .6958(5)  .4738(2)  .2874(1)  .090(2)  Uani  ?    ?
      C31  .4869(6)  .3929(2)  .4143(2)  .059(2)  Uani  ?    ?
     # - - - - data truncated for brevity - - - -
      H321C  .04(1)  .318(3)   .320(2)   .14000   Uiso  ?    ?
      H322A  .25(1)  .272(4)   .475(3)   .19000   Uiso  ?    ?
      H322B  .34976  .22118    .40954    .19000   Uiso  calc C322
      H322C  .08(1)  .234(4)   .397(3)   .19000   Uiso  ?    ?
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _atom_site_aniso_label
    _atom_site_aniso_B_11
    _atom_site_aniso_B_22
    _atom_site_aniso_B_33
    _atom_site_aniso_B_12
    _atom_site_aniso_B_13
    _atom_site_aniso_B_23
    _atom_site_aniso_type_symbol
     O1   .071(1) .076(1) .0342(9) .008(1)   .0051(9) -.0030(9) O
     C2   .060(2) .072(2) .047(1)  .002(2)   .013(1)  -.009(1)  C
     C3   .038(1) .060(2) .044(1)  .007(1)   .001(1)  -.005(1)  C
     N4   .037(1) .048(1) .0325(9) .0025(9)  .0011(9) -.0011(9) N
     C5   .043(1) .060(1) .032(1)  .001(1)  -.001(1)   .001(1)  C
     # - - - - data truncated for brevity - - - -
     O21  .094(2) .109(2) .068(1)  .023(2)   .038(1)  -.010(1)  O
     C51  .048(2) .059(2) .049(1)  .002(1)  -.000(1)   .007(1)  C
     C511 .048(2) .071(2) .097(3) -.008(2)  -.003(2)   .010(2)  C
     C512 .078(2) .083(2) .075(2)  .009(2)  -.005(2)   .033(2)  C
     C513 .074(2) .055(2) .075(2)  .004(2)   .001(2)  -.010(2)  C
     # - - - - data truncated for brevity - - - -
;
;
    Example 2 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _atom_site_label
    _atom_site_chemical_conn_number
    _atom_site_fract_x
    _atom_site_fract_y
    _atom_site_fract_z
    _atom_site_U_iso_or_equiv
     S1  1  0.74799(9)  -0.12482(11)  0.27574(9)  0.0742(3)
     S2  2  1.08535(10)  0.16131(9)   0.34061(9)  0.0741(3)
     N1  3  1.0650(2)   -0.1390(2)    0.2918(2)   0.0500(5)
     C1  4  0.9619(3)   -0.0522(3)    0.3009(2)   0.0509(6)
     # - - - - data truncated for brevity - - - -
;
;
    Example 3 - based on data set DPTD of Yamin, Suwandi, Fun, Sivakumar &
                bin Shawkataly [Acta Cryst. (1996), C52, 951-953].
;

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
     loop_
      _atom_site_label                  # *_assembly 'M' is a disordered methyl
      _atom_site_occupancy              # with configurations 'A' and 'B':
      _atom_site_disorder_assembly      #
      _atom_site_disorder_group         #    H11B    H11A      H13B
                                        #      .      |      .
   C1     1      .       .              #        .    |    .
   H11A   .5     M       A              #          .  |  .
   H12A   .5     M       A              #             C1 --------C2---
   H13A   .5     M       A              #           / .  \
   H11B   .5     M       B              #         /   .    \
   H12B   .5     M       B              #       /     .      \
   H13B   .5     M       B              #    H12A    H12B    H13A

;
;
    Example 4 - hypothetical example to illustrate the description of a
                disordered methyl group.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      _definition
;              Data items in the ATOM_SITE category record details about
               the atom sites in a crystal structure, such as the positional
               coordinates, atomic displacement parameters, and magnetic moments
               and directions.
;

data_atom_site_adp_type
    _name                      '_atom_site_adp_type'
    _category                    atom_site
    _type                        char
    _related_item              '_atom_site_thermal_displace_type'
    _related_function            alternate
    _list                        yes
    _list_reference            '_atom_site_label'
    loop_ _enumeration
          _enumeration_detail    Uani   'anisotropic Uij'
                                 Uiso   'isotropic U'
                                 Uovl   'overall U'
                                 Umpe   'multipole expansion U'
                                 Bani   'anisotropic Bij'
                                 Biso   'isotropic B'
                                 Bovl   'overall B'
    _definition
;              A standard code used to describe the type of atomic displacement
               parameters used for the site.
;

data_atom_site_aniso_B_
    loop_ _name                '_atom_site_aniso_B_11'
                               '_atom_site_aniso_B_12'
                               '_atom_site_aniso_B_13'
                               '_atom_site_aniso_B_22'
                               '_atom_site_aniso_B_23'
                               '_atom_site_aniso_B_33'
    _category                    atom_site
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_atom_site_aniso_label'
    _related_item              '_atom_site_aniso_U_'
    _related_function            conversion
    _units                       A^2^
    _units_detail              'angstroms squared'
    _definition
;              These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the 
               structure-factor term

               T = exp{-(1/4) sum~i~ [ sum~j~ (B^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

data_atom_site_aniso_label
    _name                      '_atom_site_aniso_label'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_link_parent          '_atom_site_label'
    _definition
;              Anisotropic atomic displacement parameters are usually looped in
               a separate list. If this is the case, this code must match the
               _atom_site_label of the associated atom in the atom coordinate
               list and conform with the same rules described in
               _atom_site_label.
;

data_atom_site_aniso_ratio
    _name                      '_atom_site_aniso_ratio'
    _category                    atom_site
    _type                        numb
    _list                        yes
    _list_reference            '_atom_site_aniso_label'
    _enumeration_range           1.0:
    _definition
;              Ratio of the maximum to minimum principal axes of
               displacement (thermal) ellipsoids.
;

data_atom_site_aniso_type_symbol
    _name                      '_atom_site_aniso_type_symbol'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_aniso_label'
    _list_link_parent          '_atom_site_type_symbol'
    _definition
;              This _atom_type_symbol code links the anisotropic atom
               parameters to the atom-type data associated with this site and
               must match one of the _atom_type_symbol codes in this list.
;

data_atom_site_aniso_U_
    loop_ _name                '_atom_site_aniso_U_11'
                               '_atom_site_aniso_U_12'
                               '_atom_site_aniso_U_13'
                               '_atom_site_aniso_U_22'
                               '_atom_site_aniso_U_23'
                               '_atom_site_aniso_U_33'
    _category                    atom_site
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_atom_site_aniso_label'
    _related_item              '_atom_site_aniso_B_'
    _related_function            conversion
    _units                      A^2^
    _units_detail              'angstroms squared'
    _definition
;              These are the standard anisotropic atomic displacement
               components in angstroms squared which appear in the
               structure-factor term

               T = exp{-2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }

               h = the Miller indices
               a* = the reciprocal-space cell lengths

               The unique elements of the real symmetric matrix are
               entered by row.
;

data_atom_site_attached_hydrogens
    _name                      '_atom_site_attached_hydrogens'
    _category                    atom_site
    _type                        numb
    _list                        yes
    _list_reference            '_atom_site_label'
    _enumeration_range           0:8
    _enumeration_default         0
    loop_ _example
          _example_detail        2    'water oxygen'
                                 1    'hydroxyl oxygen'
                                 4    'ammonium nitrogen'
    _definition
;              The number of hydrogen atoms attached to the atom at this site
               excluding any hydrogen atoms for which coordinates (measured or
               calculated) are given.
;

data_atom_site_B_equiv_geom_mean
    _name                      '_atom_site_B_equiv_geom_mean'
    _category                    atom_site
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_atom_site_label'
    _enumeration_range           0.0:
    loop_ _related_item
          _related_function    '_atom_site_B_iso_or_equiv'     alternate
                               '_atom_site_U_equiv_geom_mean'  conversion
    _units                       A^2^
    _units_detail              'angstroms squared'
    _definition
;              Equivalent isotropic atomic displacement parameter, B(equiv),
               in angstroms squared, calculated as the geometric mean of
               the anisotropic atomic displacement parameters.

               B(equiv) = (B~i~ B~j~ B~k~)^1/3^

               B~n~  = the principal components of the orthogonalized B^ij^

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

data_atom_site_B_iso_or_equiv
    _name                      '_atom_site_B_iso_or_equiv'
    _category                    atom_site
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_atom_site_label'
    _enumeration_range           0.0:
    loop_ _related_item
          _related_function    '_atom_site_B_equiv_geom_mean'  alternate
                               '_atom_site_U_iso_or_equiv'     conversion
    _units                       A^2^
    _units_detail              'angstroms squared'
    _definition
;              Isotropic atomic displacement parameter, or equivalent isotropic
               atomic displacement parameter, B(equiv), in angstroms squared,
               calculated from anisotropic displacement components.

               B(equiv) = (1/3) sum~i~[sum~j~(B^ij^ a*~i~ a*~j~ a~i~ a~j~)]

               a     = the real-space cell lengths
               a*    = the reciprocal-space cell lengths
               B^ij^ = 8 pi^2^ U^ij^

               Ref: Fischer, R. X. & Tillmanns, E. (1988). Acta Cryst. C44,
                    775-776.

               The IUCr Commission on Nomenclature recommends against the use
               of B for reporting atomic displacement parameters. U, being
               directly proportional to B, is preferred.
;

data_atom_site_calc_attached_atom
    _name                      '_atom_site_calc_attached_atom'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    _enumeration_default        '.'
    _definition
;              The _atom_site_label of the atom site to which the 'geometry-
               calculated' atom site is attached.
;

data_atom_site_calc_flag
    _name                      '_atom_site_calc_flag'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    loop_ _enumeration
          _enumeration_detail   d     'determined from diffraction measurements'
                                calc  'calculated from molecular geometry'
                                c     'abbreviation for "calc"'
                                dum   'dummy site with meaningless coordinates'
    _enumeration_default        d
    _definition
;              A standard code to signal whether the site coordinates have been
               determined from the intensities or calculated from the geometry
               of surrounding sites, or have been assigned dummy coordinates.
               The abbreviation 'c' may be used in place of 'calc'.
;

data_atom_site_Cartn_
    loop_ _name                '_atom_site_Cartn_x'
                               '_atom_site_Cartn_y'
                               '_atom_site_Cartn_z'
    _category                    atom_site
    _type                        numb
    _type_conditions             esd
    _related_item              '_atom_site_fract_'
    _related_function            alternate
    _list                        yes
    _list_reference            '_atom_site_label'
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The atom-site coordinates in angstroms specified according to a
               set of orthogonal Cartesian axes related to the cell axes as
               specified by the _atom_sites_Cartn_transform_axes description.
;

data_atom_site_chemical_conn_number
    _name                      '_atom_site_chemical_conn_number'
    _category                    atom_site
    _type                        numb
    _list                        yes
    _list_link_parent          '_chemical_conn_atom_number'
    _list_reference            '_atom_site_label'
    _enumeration_range           1:
    _definition
;              This number links an atom site to the chemical connectivity list.
               It must match a number specified by _chemical_conn_atom_number.
;

data_atom_site_constraints
    _name                      '_atom_site_constraints'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    _enumeration_default        '.'
    _example                    'pop=1.0-pop(Zn3)'
    _definition
;              A description of the constraints applied to parameters at this
               site during refinement. See also _atom_site_refinement_flags
               and _refine_ls_number_constraints.
;

data_atom_site_description
    _name                      '_atom_site_description'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    _example                    'Ag/Si disordered'
    _definition
;              A description of special aspects of this site. See also
               _atom_site_refinement_flags.
;

data_atom_site_disorder_assembly
    _name                      '_atom_site_disorder_assembly'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    loop_ _example
          _example_detail   A  'disordered methyl assembly with groups 1 and 2'
                            B  'disordered sites related by a mirror'
                            S  'disordered sites independent of symmetry'
    _definition
;              A code which identifies a cluster of atoms that show long-range
               positional disorder but are locally ordered. Within each such
               cluster of atoms, _atom_site_disorder_group is used to identify
               the sites that are simultaneously occupied. This field is only
               needed if there is more than one cluster of disordered atoms
               showing independent local order.
;

data_atom_site_disorder_group
    _name                      '_atom_site_disorder_group'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    loop_ _example
          _example_detail    1  'unique disordered site in group 1'
                             2  'unique disordered site in group 2'
                            -1  'symmetry-independent disordered site'
    _definition
;              A code which identifies a group of positionally disordered atom
               sites that are locally simultaneously occupied. Atoms that are
               positionally disordered over two or more sites (e.g. the hydrogen
               atoms of a methyl group that exists in two orientations) can
               be assigned to two or more groups. Sites belonging to the same
               group are simultaneously occupied, but those belonging to
               different groups are not. A minus prefix (e.g. "-1") is used to
               indicate sites disordered about a special position.
;

data_atom_site_fract_
    loop_ _name                '_atom_site_fract_x'
                               '_atom_site_fract_y'
                               '_atom_site_fract_z'
    _category                    atom_site
    _type                        numb
    _type_conditions             esd
    _related_item              '_atom_site_Cartn_'
    _related_function            alternate
    _list                        yes
    _list_reference            '_atom_site_label'
    _definition
;              Atom-site coordinates as fractions of the _cell_length_ values.
;

data_atom_site_label
    _name                      '_atom_site_label'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_mandatory              yes
    loop_ _list_link_child     '_atom_site_aniso_label'
                               '_geom_angle_atom_site_label_1'
                               '_geom_angle_atom_site_label_2'
                               '_geom_angle_atom_site_label_3'
                               '_geom_bond_atom_site_label_1'
                               '_geom_bond_atom_site_label_2'
                               '_geom_contact_atom_site_label_1'
                               '_geom_contact_atom_site_label_2'
                               '_geom_hbond_atom_site_label_D'
                               '_geom_hbond_atom_site_label_H'
                               '_geom_hbond_atom_site_label_A'
                               '_geom_torsion_atom_site_label_1'
                               '_geom_torsion_atom_site_label_2'
                               '_geom_torsion_atom_site_label_3'
                               '_geom_torsion_atom_site_label_4'
    loop_ _example               C12     Ca3g28     Fe3+17     H*251
                                 boron2a   C_a_phe_83_a_0  Zn_Zn_301_A_0
    _definition
;              The _atom_site_label is a unique identifier for a particular site
               in the crystal. This code is made up of a sequence of up to seven
               components, _atom_site_label_component_0 to *_6, which may be
               specified as separate data items. Component 0 usually matches one
               of the specified _atom_type_symbol codes. This is not mandatory
               if an _atom_site_type_symbol item is included in the atom-site
               list. The _atom_site_type_symbol always takes precedence over
               an _atom_site_label in the identification of the atom type. The
               label components 1 to 6 are optional, and normally only
               components 0 and 1 are used. Note that components 0 and 1 are
               concatenated, while all other components, if specified, are
               separated by an underscore. Underscores are
               only used if higher-order components exist. If an intermediate
               component is not used, it may be omitted provided the underscore
               separators are inserted. For example, the label 'C233__ggg' is
               acceptable and represents the components C, 233, '' and ggg.
               Different labels may have a different number of components.
;

data_atom_site_label_component_
    loop_ _name                '_atom_site_label_component_0'
                               '_atom_site_label_component_1'
                               '_atom_site_label_component_2'
                               '_atom_site_label_component_3'
                               '_atom_site_label_component_4'
                               '_atom_site_label_component_5'
                               '_atom_site_label_component_6'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    _definition
;              Component 0 is normally a code which matches identically with
               one of the _atom_type_symbol codes. If this is the case, then the
               rules governing the _atom_type_symbol code apply. If, however,
               the data item _atom_site_type_symbol is also specified in the
               atom-site list, component 0 need not match this symbol or adhere
               to any of the _atom_type_symbol rules.
               Component 1 is referred to as the "atom number". When component 0
               is the atom-type code, it is used to number the sites with the
               same atom type. This component code must start with at least one
               digit which is not followed by a + or - sign (to distinguish it
               from the component 0 rules).
               Components 2 to 6 contain the identifier, residue, sequence,
               asymmetry identifier and alternate codes, respectively. These
               codes may be composed of any characters except an underscore.
;

data_atom_site_occupancy
    _name                      '_atom_site_occupancy'
    _category                    atom_site
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_atom_site_label'
    _enumeration_range           0.0:1.0
    _enumeration_default         1.0
    _definition
;              The fraction of the atom type present at this site.
               The sum of the occupancies of all the atom types at this site
               may not significantly exceed 1.0 unless it is a dummy site. The
               value must lie in the 99.97% Gaussian confidence interval
               -3u =< x =< 1 + 3u. The _enumeration_range of 0.0:1.0 is thus
               correctly interpreted as meaning (0.0 - 3u) =< x =< (1.0 + 3u).
;

data_atom_site_refinement_flags
    _name                      '_atom_site_refinement_flags'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
  loop_
   _related_item
   _related_function
                               '_atom_site_refinement_flags_posn'      replace
                               '_atom_site_refinement_flags_adp'       replace
                               '_atom_site_refinement_flags_occupancy' replace
   loop_ _enumeration
         _enumeration_detail   . 'no refinement constraints'
                               S 'special-position constraint on site'
                               G 'rigid-group refinement of site'
                               R 'riding-atom site attached to non-riding atom'
                               D 'distance or angle restraint on site'
                               T 'thermal displacement constraints'
                               U 'Uiso or Uij restraint (rigid bond)'
                               P 'partial occupancy constraint'
   _definition
;           A concatenated series of single-letter codes which indicate the
            refinement restraints or constraints applied to this site.  This
            item should not be used.  It has been replaced by
            _atom_site_refinement_flags_posn, *_adp and *_occupancy. It is
            retained in this dictionary only to provide compatibility with
            legacy CIFs.
;

data_atom_site_refinement_flags_adp
    _name                      '_atom_site_refinement_flags_adp'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    _related_item              '_atom_site_refinement_flags'
    _related_function            alternate
    loop_ _enumeration
          _enumeration_detail
             .  'no constraints on atomic displacement parameters'
             T  'special-position constraints on atomic displacement parameters'
             U  'Uiso or Uij restraint (rigid bond)'
             TU 'both constraints applied'
    _definition
;              A code which indicates the refinement restraints or constraints
               applied to the atomic displacement parameters of this site.
;

data_atom_site_refinement_flags_occupancy
    _name                      '_atom_site_refinement_flags_occupancy'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    _related_item              '_atom_site_refinement_flags'
    _related_function            alternate
    loop_ _enumeration
          _enumeration_detail   . 'no constraints on site-occupancy parameters'
                                P 'site-occupancy constraint'
    _definition
;              A code which indicates that refinement restraints or
               constraints were applied to the occupancy of this site.
;

data_atom_site_refinement_flags_posn
    _name                      '_atom_site_refinement_flags_posn'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    _related_item              '_atom_site_refinement_flags'
    _related_function            alternate
    loop_ _enumeration
          _enumeration_detail
                     . 'no constraints on  positional coordinates'
                     D 'distance or angle restraint on positional coordinates'
                     G 'rigid-group refinement of positional coordinates'
                     R 'riding-atom site attached to non-riding atom'
                     S 'special-position constraint on positional coordinates'
                     DG   'combination of the above constraints'
                     DR   'combination of the above constraints'
                     DS   'combination of the above constraints'
                     GR   'combination of the above constraints'
                     GS   'combination of the above constraints'
                     RS    'combination of the above constraints'
                     DGR  'combination of the above constraints'
                     DGS  'combination of the above constraints'
                     DRS  'combination of the above constraints'
                     GRS  'combination of the above constraints'
                     DGRS 'combination of the above constraints'
    _definition
;              A code which indicates the refinement restraints or constraints
               applied to the positional coordinates of this site.
;

data_atom_site_restraints
    _name                      '_atom_site_restraints'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    _example                    'restrained to planar ring'
    _definition
;              A description of restraints applied to specific parameters at
               this site during refinement. See also _atom_site_refinement_flags
               and _refine_ls_number_restraints.
;

data_atom_site_symmetry_multiplicity
    _name                      '_atom_site_symmetry_multiplicity'
    _category                    atom_site
    _type                        numb
    _list                        yes
    _list_reference            '_atom_site_label'
    _enumeration_range           1:192
    _definition
;              The multiplicity of a site due to the space-group symmetry as
               given in International Tables for Crystallography Vol. A (2002).
;

data_atom_site_thermal_displace_type
    _name                      '_atom_site_thermal_displace_type'
    _category                    atom_site
    _type                        char
    _related_item              '_atom_site_adp_type'
    _related_function            replace
    _list                        yes
    _list_reference            '_atom_site_label'
    loop_ _enumeration
          _enumeration_detail    Uani   'anisotropic Uij'
                                 Uiso   'isotropic U'
                                 Uovl   'overall U'
                                 Umpe   'multipole expansion U'
                                 Bani   'anisotropic Bij'
                                 Biso   'isotropic B'
                                 Bovl   'overall B'
    _definition
;              A standard code used to describe the type of atomic displacement
               parameters used for the site.
;

data_atom_site_type_symbol
    _name                      '_atom_site_type_symbol'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    _list_link_parent          '_atom_type_symbol'
    _list_link_child           '_atom_site_aniso_type_symbol'
    loop_ _example               Cu   Cu2+   dummy   Fe3+Ni2+
                                 S-   H*     H(SDS)
    _definition
;              A code to identify the atom species (singular or plural)
               occupying this site.
               This code must match a corresponding _atom_type_symbol. The
               specification of this code is optional if component 0 of the
               _atom_site_label is used for this purpose. See _atom_type_symbol.
;

data_atom_site_U_equiv_geom_mean
    _name                      '_atom_site_U_equiv_geom_mean'
    _category                    atom_site
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_atom_site_label'
    _enumeration_range           0.0:
    loop_ _related_item
          _related_function    '_atom_site_U_iso_or_equiv'     alternate
                               '_atom_site_B_equiv_geom_mean'  conversion
    _units                       A^2^
    _units_detail              'angstroms squared'
    _definition
;              Equivalent isotropic atomic displacement parameter, U(equiv),
               in angstroms squared, calculated as the geometric mean of
               the anisotropic atomic displacement parameters.

               U(equiv) = (U~i~ U~j~ U~k~)^1/3^

               U~n~  = the principal components of the orthogonalized U^ij^
;

data_atom_site_U_iso_or_equiv
    _name                      '_atom_site_U_iso_or_equiv'
    _category                    atom_site
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_atom_site_label'
    _enumeration_range           0.0:
    loop_ _related_item
          _related_function    '_atom_site_U_equiv_geom_mean'  alternate
                               '_atom_site_B_iso_or_equiv'     conversion
    _units                       A^2^
    _units_detail              'angstroms squared'
    _definition
;              Isotropic atomic displacement parameter, or equivalent isotropic
               atomic  displacement parameter, U(equiv), in angstroms squared,
               calculated from anisotropic atomic displacement  parameters.

               U(equiv) = (1/3) sum~i~[sum~j~(U^ij^ a*~i~ a*~j~ a~i~ a~j~)]

               a     = the real-space cell lengths
               a*    = the reciprocal-space cell lengths

               Ref: Fischer, R. X. & Tillmanns, E. (1988). Acta Cryst. C44,
                    775-776.
;

data_atom_site_Wyckoff_symbol
    _name                      '_atom_site_Wyckoff_symbol'
    _category                    atom_site
    _type                        char
    _list                        yes
    _list_reference            '_atom_site_label'
    _definition
;              The Wyckoff symbol (letter) as listed in the space-group tables
               of International Tables for Crystallography Vol. A (2002).
;

################
## ATOM_SITES ##
################

data_atom_sites_[]
    _name                      '_atom_sites_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _atom_sites_Cartn_transform_axes
          'c along z, astar along x, b along y'

    _atom_sites_Cartn_tran_matrix_11    58.39
    _atom_sites_Cartn_tran_matrix_12     0.00
    _atom_sites_Cartn_tran_matrix_13     0.00
    _atom_sites_Cartn_tran_matrix_21     0.00
    _atom_sites_Cartn_tran_matrix_22    86.70
    _atom_sites_Cartn_tran_matrix_23     0.00
    _atom_sites_Cartn_tran_matrix_31     0.00
    _atom_sites_Cartn_tran_matrix_32     0.00
    _atom_sites_Cartn_tran_matrix_33    46.27

;
;
    Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the ATOM_SITES category record details about
               the crystallographic cell and cell transformations, which are
               common to all atom sites.
;

data_atom_sites_Cartn_tran_matrix_
    loop_ _name                '_atom_sites_Cartn_tran_matrix_11'
                               '_atom_sites_Cartn_tran_matrix_12'
                               '_atom_sites_Cartn_tran_matrix_13'
                               '_atom_sites_Cartn_tran_matrix_21'
                               '_atom_sites_Cartn_tran_matrix_22'
                               '_atom_sites_Cartn_tran_matrix_23'
                               '_atom_sites_Cartn_tran_matrix_31'
                               '_atom_sites_Cartn_tran_matrix_32'
                               '_atom_sites_Cartn_tran_matrix_33'
    _category                    atom_sites
    _type                        numb
    _definition
;              Matrix elements used to transform fractional coordinates in
               the ATOM_SITE category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_Cartn_tran_vector_.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

data_atom_sites_Cartn_tran_vector_
    loop_ _name                '_atom_sites_Cartn_tran_vector_1'
                               '_atom_sites_Cartn_tran_vector_2'
                               '_atom_sites_Cartn_tran_vector_3'
    _category                    atom_sites
    _type                        numb
    _definition
;              Elements of a 3 x 1 translation vector used in the
               transformation of fractional coordinates in the
               ATOM_SITE category to Cartesian  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes.
                 x'                   |11 12 13|      x                  | 1 |
               ( y' ) Cartesian   =   |21 22 23|    ( y ) fractional  +  | 2 |
                 z'                   |31 32 33|      z                  | 3 |
;

data_atom_sites_Cartn_transform_axes
    _name                      '_atom_sites_Cartn_transform_axes'
    _category                    atom_sites
    _type                        char
    _example                    'a parallel to x; b in the plane of y and z'
    _definition
;              A description of the relative alignment of the crystal cell
               axes to the  Cartesian orthogonal axes as applied in the
               transformation matrix _atom_sites_Cartn_tran_matrix_.
;


data_atom_sites_fract_tran_matrix_
    loop_ _name                 '_atom_sites_fract_tran_matrix_11'
                                '_atom_sites_fract_tran_matrix_12'
                                '_atom_sites_fract_tran_matrix_13'
                                '_atom_sites_fract_tran_matrix_21'
                                '_atom_sites_fract_tran_matrix_22'
                                '_atom_sites_fract_tran_matrix_23'
                                '_atom_sites_fract_tran_matrix_31'
                                '_atom_sites_fract_tran_matrix_32'
                                '_atom_sites_fract_tran_matrix_33'
    _category                    atom_sites
    _type                        numb
    _definition
;              Matrix elements used to transform Cartesian coordinates in
               the ATOM_SITE category to fractional coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes. The 3 x 1 translation is
               defined in _atom_sites_fract_tran_vector_.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

data_atom_sites_fract_tran_vector_
    loop_ _name                '_atom_sites_fract_tran_vector_1'
                               '_atom_sites_fract_tran_vector_2'
                               '_atom_sites_fract_tran_vector_3'
    _category                    atom_sites
    _type                        numb
    _definition
;              Elements of a 3 x 1 translation vector used in the
               transformation of Cartesian coordinates in the
               ATOM_SITE category to fractional  coordinates. The axial
               alignments of this transformation are described in
               _atom_sites_Cartn_transform_axes.
                 x'                   |11 12 13|      x                 | 1 |
               ( y' ) fractional  =   |21 22 23|    ( y ) Cartesian  +  | 2 |
                 z'                   |31 32 33|      z                 | 3 |
;

data_atom_sites_solution_
    loop_ _name                '_atom_sites_solution_primary'
                               '_atom_sites_solution_secondary'
                               '_atom_sites_solution_hydrogens'
    _category                    atom_sites
    _type                        char
    loop_ _enumeration
          _enumeration_detail    difmap  'difference Fourier map'
                                 vecmap  'real-space vector search'
                                 heavy   'heavy-atom method'
                                 direct  'structure-invariant direct methods'
                                 geom    'inferred from neighbouring sites'
                                 disper  'anomalous-dispersion techniques'
                                 isomor  'isomorphous structure methods'
                                 notdet  'coordinates were not determined'
                                 dual
                                    'dual-space method (Sheldrick et al., 2001)'
                                 other
                                  'a method not included elsewhere in this list'
    _definition
;              Codes which identify the methods used to locate the initial
               atom sites. The *_primary code identifies how the first
               atom sites were determined; the *_secondary code identifies
               how the remaining non-hydrogen sites were located; and the
               *_hydrogens code identifies how the hydrogen sites were located.

               Ref: Sheldrick, G. M., Hauptman, H. A., Weeks, C. M.,
                    Miller, R. and Us\'on, I. (2001). Ab initio phasing.
                    In International Tables for Crystallography,
                    Vol. F. Crystallography of biological macromolecules,
                    edited by M. G. Rossmann and E. Arnold, ch. 16.1.
                    Dordrecht: Kluwer Academic Publishers.
;

data_atom_sites_special_details
    _name                      '_atom_sites_special_details'
    _category                    atom_sites
    _type                        char
    _definition
;              Additional information about the atomic coordinates not coded
               elsewhere in the CIF.
;

###############
## ATOM_TYPE ##
###############

data_atom_type_[]
    _name                      '_atom_type_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _atom_type_symbol
    _atom_type_oxidation_number
    _atom_type_number_in_cell
    _atom_type_scat_dispersion_real
    _atom_type_scat_dispersion_imag
    _atom_type_scat_source
      C 0 72  .017  .009  International_Tables_Vol_IV_Table_2.2B
      H 0 100  0     0    International_Tables_Vol_IV_Table_2.2B
      O 0 12  .047  .032  International_Tables_Vol_IV_Table_2.2B
      N 0 4   .029  .018  International_Tables_Vol_IV_Table_2.2B
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the ATOM_TYPE category record details about
               properties of the atoms that occupy the atom sites, such as the
               atomic scattering factors.
;

data_atom_type_analytical_mass_%
    _name                      '_atom_type_analytical_mass_%'
    _category                    atom_type
    _type                        numb
    _list                        yes
    _list_reference            '_atom_type_symbol'
    _enumeration_range           0.0:100.0
    _definition
;              Mass percentage of this atom type derived from chemical analysis.
;

data_atom_type_description
    _name                      '_atom_type_description'
    _category                    atom_type
    _type                        char
    _list                        yes
    _list_reference            '_atom_type_symbol'
    loop_ _example               deuterium       0.34Fe+0.66Ni
    _definition
;              A description of the atom(s) designated by this atom type. In
               most cases, this will be the element name and oxidation state of
               a single atom  species. For disordered or nonstoichiometric
               structures it will describe a combination of atom species.
;

data_atom_type_number_in_cell
    _name                      '_atom_type_number_in_cell'
    _category                    atom_type
    _type                        numb
    _list                        yes
    _list_reference            '_atom_type_symbol'
    _enumeration_range           0:
    _definition
;              Total number of atoms of this atom type in the unit cell.
;

data_atom_type_oxidation_number
    _name                      '_atom_type_oxidation_number'
    _category                    atom_type
    _type                        numb
    _list                        yes
    _list_reference            '_atom_type_symbol'
    _enumeration_range           -8:8
    _enumeration_default         0
    _definition
;              Formal oxidation state of this atom type in the structure.
;

data_atom_type_radius_
    loop_ _name                '_atom_type_radius_bond'
                               '_atom_type_radius_contact'
    _category                    atom_type
    _type                        numb
    _list                        yes
    _list_reference            '_atom_type_symbol'
    _enumeration_range           0.0:5.0
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The effective intra- and intermolecular bonding radii in
               angstroms of this atom type.
;

data_atom_type_scat_Cromer_Mann_
    loop_ _name                '_atom_type_scat_Cromer_Mann_a1'
                               '_atom_type_scat_Cromer_Mann_a2'
                               '_atom_type_scat_Cromer_Mann_a3'
                               '_atom_type_scat_Cromer_Mann_a4'
                               '_atom_type_scat_Cromer_Mann_b1'
                               '_atom_type_scat_Cromer_Mann_b2'
                               '_atom_type_scat_Cromer_Mann_b3'
                               '_atom_type_scat_Cromer_Mann_b4'
                               '_atom_type_scat_Cromer_Mann_c'
    _category                    atom_type
    _type                        numb
    _list                        yes
    _list_reference            '_atom_type_symbol'
    _definition
;              The Cromer-Mann scattering-factor coefficients used to calculate
               the scattering factors for this atom type.

               Ref: International Tables for X-ray Crystallography (1974). 
                     Vol. IV, Table 2.2B
               or   International Tables for Crystallography (2004). Vol. C,
                    Tables 6.1.1.4 and 6.1.1.5
;

data_atom_type_scat_dispersion_
    loop_ _name                '_atom_type_scat_dispersion_imag'
                               '_atom_type_scat_dispersion_real'
    _category                    atom_type
    _type                        numb
    _list                        yes
    _list_reference            '_atom_type_symbol'
    _enumeration_default         0.0
    _definition
;              The imaginary and real components of the anomalous-dispersion
               scattering factor, f'' and f', in electrons for this atom type
               and the radiation given in _diffrn_radiation_wavelength.
;

data_atom_type_scat_dispersion_source
    _name                      '_atom_type_scat_dispersion_source'
    _category                    atom_type
    _type                        char
    _list                        yes
    _list_reference            '_atom_type_symbol'
    _example                   'International Tables Vol. IV Table 2.3.1'
    _definition
;              Reference to source of real and imaginary dispersion
               corrections for scattering factors used for this atom type.
;

data_atom_type_scat_length_neutron
    _name                      '_atom_type_scat_length_neutron'
    _category                    atom_type
    _type                        numb
    _list                        yes
    _list_reference            '_atom_type_symbol'
    _enumeration_default         0.0
    _units                       fm
    _units_detail              'femtometres'
    _definition
;              The bound coherent scattering length in femtometres for the
               atom type at the isotopic composition used for the diffraction
               experiment.
;

data_atom_type_scat_source
    _name                      '_atom_type_scat_source'
    _category                    atom_type
    _type                        char
    _list                        yes
    _list_reference            '_atom_type_symbol'
    _example                   'International Tables Vol. IV Table 2.4.6B'
    _definition
;              Reference to source of scattering factors or scattering lengths
               used for this atom type.
;

data_atom_type_scat_versus_stol_list
    _name                      '_atom_type_scat_versus_stol_list'
    _category                    atom_type
    _type                        char
    _list                        yes
    _list_reference            '_atom_type_symbol'
    _definition
;              A table of scattering factors as a function of sin theta over
               lambda. This table should be well commented to indicate the
               items present. Regularly formatted lists are strongly
               recommended.
;

data_atom_type_symbol
    _name                      '_atom_type_symbol'
    _category                    atom_type
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_child           '_atom_site_type_symbol'
    loop_ _example               C   Cu2+   H(SDS)    dummy    FeNi
    _definition
;              The code used to identify the atom species (singular or plural)
               representing this atom type. Normally this code is the element
               symbol. The code may be composed of any character except an
               underscore with the additional proviso that digits designate an
               oxidation state and must be followed by a + or - character.
;

###########
## AUDIT ##
###########

data_audit_[]
    _name                      '_audit_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _audit_block_code                  TOZ_1991-03-20

    _audit_creation_date               1991-03-20
    _audit_creation_method   from_xtal_archive_file_using_CIFIO
    _audit_update_record
    ; 1991-04-09     text and data added by Tony Willis.
      1991-04-15     rec'd by co-editor as manuscript HL0007.
      1991-04-17     adjustments based on first referee report.
      1991-04-18     adjustments based on second referee report.
    ;
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the AUDIT category record details about the
               creation and subsequent updating of the data block.
;

data_audit_block_code
    _name                      '_audit_block_code'
    _category                    audit
    _type                        char
    _example                     TOZ_1991-03-20
    _definition
;              A code intended to identify uniquely the current data block.
;

data_audit_creation_date
    _name                      '_audit_creation_date'
    _category                    audit
    _type                        char
    _example                     1990-07-12
    _definition
;              The date that the data block was created. The date format
               is yyyy-mm-dd.
;

data_audit_creation_method
    _name                      '_audit_creation_method'
    _category                    audit
    _type                        char
    _example                    'spawned by the program QBEE'
    _definition
;              A description of how data were entered into the data block.
;

data_audit_update_record
    _name                      '_audit_update_record'
    _category                    audit
    _type                        char
    _example                    '1990-07-15   Updated by the Co-editor'
    _definition
;              A record of any changes to the data block. The update format
               is a date (yyyy-mm-dd) followed by a description of the
               changes. The latest update entry is added to the bottom of
               this record.
;

##################
## AUDIT_AUTHOR ##
##################

data_audit_author_[]
    _name                      '_audit_author_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _audit_author_name
    _audit_author_address
        'Fitzgerald, Paula M. D.'
    ;  Department of Biophysical Chemistry
       Merck Research Laboratories
       PO Box 2000, Ry80M203
       Rahway
       New Jersey 07065
       USA
    ;
        'Van Middlesworth, J. F.'
    ;  Department of Biophysical Chemistry
       Merck Research Laboratories
       PO Box 2000, Ry80M203
       Rahway
       New Jersey 07065
       USA
    ;
;
;
    Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the AUDIT_AUTHOR category record details about
               the author(s) of the data block.
;

data_audit_author_address
    _name                      '_audit_author_address'
    _category                    audit_author
    _type                        char
    _list                        yes
    _list_reference            '_audit_author_name'
    _example
;                       Department
                        Institute
                        Street
                        City and postcode
                        COUNTRY
;
    _definition
;              The address of an author of this data block. If there are
               multiple authors, _audit_author_address is looped with
               _audit_author_name.
;

data_audit_author_name
    _name                      '_audit_author_name'
    _category                    audit_author
    _type                        char
    _list                        yes
    _list_mandatory              yes
    loop_ _example             'Bleary, Percival R.'
                               "O'Neil, F.K."
                               'Van den Bossche, G.'
                               'Yang, D.-L.'
                               'Simonov, Yu.A.'
                               'M\"uller, H.A.'
                               'Ross II, C.R.'
    _definition
;              The name of an author of this data block. If there are multiple
               authors, _audit_author_name is looped with _audit_author_address.
               The family name(s), followed by a comma and including any
               dynastic components, precedes the first name(s) or initial(s).
;

###################
## AUDIT_CONFORM ##
###################

data_audit_conform_[]
    _name                      '_audit_conform_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _audit_conform_dict_name         cif_core.dic
    _audit_conform_dict_version      2.4
    _audit_conform_dict_location
          ftp://ftp.iucr.org/pub/cif_core.2.4.dic
;
;
    Example 1 - any file conforming to the current CIF core dictionary.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the AUDIT_CONFORM category describe the
               dictionary versions against which the data names appearing in
               the current data block are conformant.
;

data_audit_conform_dict_location
    _name                      '_audit_conform_dict_location'
    _category                    audit_conform
    _type                        char
    _list                        both
    _list_reference            '_audit_conform_dict_name'
    _definition
;              A file name or uniform resource locator (URL) for the
               dictionary to which the current data block conforms.
;

data_audit_conform_dict_name
    _name                      '_audit_conform_dict_name'
    _category                    audit_conform
    _type                        char
    _list                        both
    _list_mandatory              yes
    _definition
;              The string identifying the highest-level dictionary defining
               data names used in this file.
;

data_audit_conform_dict_version
    _name                      '_audit_conform_dict_version'
    _category                    audit_conform
    _type                        char
    _list                        both
    _list_reference            '_audit_conform_dict_name'
    _definition
;              The version number of the dictionary to which the
               current data block conforms.
;

##########################
## AUDIT_CONTACT_AUTHOR ##
##########################

data_audit_contact_author_[]
    _name                      '_audit_contact_author_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _audit_contact_author_name
    _audit_contact_author_address
    _audit_contact_author_email
    _audit_contact_author_fax
    _audit_contact_author_phone
        'Fitzgerald, Paula M. D.'
    ;  Department of Biophysical Chemistry
       Merck Research Laboratories
       PO Box 2000, Ry80M203
       Rahway
       New Jersey 07065
       USA
    ;
        'paula_fitzgerald@merck.com'
        '1(908)5945510'
        '1(908)5945510'
;
;
    Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the AUDIT_CONTACT_AUTHOR category record details
               about the name and address of the author to be contacted
               concerning the contents of this data block.
;

data_audit_contact_author_address
    _name                      '_audit_contact_author_address'
    _category                    audit_contact_author
    _type                        char
    _example
;                       Department
                        Institute
                        Street
                        City and postcode
                        COUNTRY
;
    _definition
;              The mailing address of the author of the data block to whom
               correspondence should be addressed.
;

data_audit_contact_author_email
    _name                      '_audit_contact_author_email'
    _category                    audit_contact_author
    _type                        char
    loop_ _example               name@host.domain.country
                                 bm@iucr.org
    _definition
;              The electronic mail address of the author of the data block
               to whom correspondence should be addressed, in a form
               recognizable to international networks. The format of e-mail 
               addresses is given in Section 3.4, Address Specification, of 
               Internet Message Format, RFC 2822, P. Resnick (Editor), 
               Network Standards Group, April 2001.
;

data_audit_contact_author_fax
    _name                      '_audit_contact_author_fax'
    _category                    audit_contact_author
    _type                        char
     loop_
    _example                    '12(34)9477334'
                                '12()349477334'
    _definition
;              The facsimile telephone number of the author of the data
               block to whom correspondence should be addressed.

               The recommended style starts with the international dialing
               prefix, followed by the area code in parentheses, followed by the
               local number with no spaces.
;

data_audit_contact_author_name
    _name                      '_audit_contact_author_name'
    _category                    audit_contact_author
    _type                        char
    loop_ _example             'Bleary, Percival R.'
                               "O'Neil, F.K."
                               'Van den Bossche, G.'
                               'Yang, D.-L.'
                               'Simonov, Yu.A.'
                               'M\"uller, H.A.'
                               'Ross II, C.R.'
    _definition
;              The name of the author of the data block to whom correspondence
               should be addressed.

               The family name(s), followed by a comma and including any
               dynastic components, precedes the first name(s) or initial(s).
;

data_audit_contact_author_phone
    _name                      '_audit_contact_author_phone'
    _category                    audit_contact_author
    _type                        char
     loop_
    _example                    '12(34)9477330'
                                '12()349477330'
                                '12(34)9477330x5543'
    _definition
;              The telephone number of the author of the data block to whom
               correspondence should be addressed.

               The recommended style starts with the international dialing
               prefix, followed by the area code in parentheses, followed by the
               local number and any extension number prefixed by 'x',
               with no spaces.
;

################
## AUDIT_LINK ##
################

data_audit_link_[]
    _name                      '_audit_link_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _audit_link_block_code
    _audit_link_block_description
       .         'discursive text of paper with two structures'
       morA_(1)  'structure 1 of 2'
       morA_(2)  'structure 2 of 2'
;
;
    Example 1 - multiple structure paper, as illustrated
                in A Guide to CIF for Authors (1995). IUCr: Chester.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _audit_link_block_code
    _audit_link_block_description
      .       'publication details'
      KSE_COM 'experimental data common to ref./mod. structures'
      KSE_REF 'reference structure'
      KSE_MOD 'modulated structure'
;
;
    Example 2 - example file for the one-dimensional incommensurately
                modulated structure of K~2~SeO~4~.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the AUDIT_LINK category record details about the
               relationships between data blocks in the current CIF.
;

data_audit_link_block_code
    _name                      '_audit_link_block_code'
    _category                    audit_link
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _definition
;              The value of _audit_block_code associated with a data block
               in the current file related to the current data block. The
               special value '.' may be used to refer to the current data
               block for completeness.
;

data_audit_link_block_description
    _name                      '_audit_link_block_description'
    _category                    audit_link
    _type                        char
    _list                        yes
    _list_reference            '_audit_link_block_code'
    _definition
;              A textual description of the relationship of the referenced
               data block to the current one.
;

##########
## CELL ##
##########

data_cell_[]
    _name                      '_cell_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _cell_length_a                     5.959(1)
    _cell_length_b                     14.956(1)
    _cell_length_c                     19.737(3)
    _cell_angle_alpha                  90
    _cell_angle_beta                   90
    _cell_angle_gamma                  90
    _cell_volume                       1759.0(3)

    _cell_measurement_temperature      293
    _cell_measurement_reflns_used      25
    _cell_measurement_theta_min        25
    _cell_measurement_theta_max        31
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the CELL category record details about the
               crystallographic cell parameters and their measurement.
;

data_cell_angle_
    loop_ _name                '_cell_angle_alpha'
                               '_cell_angle_beta'
                               '_cell_angle_gamma'
    _category                    cell
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:180.0
    _enumeration_default         90.0
    _units                       deg
    _units_detail              'degrees'
    _definition
;              Unit-cell angles of the reported structure in degrees.
               The values of _refln_index_h, *_k, *_l must correspond to the
               cell defined by these values and _cell_length_a, *_b and *_c.
               The values of _diffrn_refln_index_h, *_k, *_l may not correspond
               to these values if a cell transformation took place following
               the measurement of the diffraction intensities. See also
               _diffrn_reflns_transf_matrix_.
;

data_cell_formula_units_Z
    _name                      '_cell_formula_units_Z'
    _category                    cell
    _type                        numb
    _enumeration_range           1:
    _definition
;              The number of the formula units in the unit cell as specified
               by _chemical_formula_structural, _chemical_formula_moiety or
               _chemical_formula_sum.
;

data_cell_length_
    loop_ _name                '_cell_length_a'
                               '_cell_length_b'
                               '_cell_length_c'
    _category                    cell
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              Unit-cell lengths in angstroms corresponding to the structure
               reported. The values of _refln_index_h, *_k, *_l must
               correspond to the cell defined by these values and _cell_angle_
               values. The values of _diffrn_refln_index_h, *_k, *_l may not
               correspond to these values if a cell transformation took place
               following the measurement of the diffraction intensities. See
               also _diffrn_reflns_transf_matrix_.
;

data_cell_measurement_pressure
    _name                      '_cell_measurement_pressure'
    _category                    cell
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _units                       kPa
    _units_detail              'kilopascals'
    _definition
;              The pressure in kilopascals at which the unit-cell parameters
               were measured (not the pressure at which the sample was
               synthesized).
;

data_cell_measurement_radiation
    _name                      '_cell_measurement_radiation'
    _category                    cell
    _type                        char
    loop_ _example              'neutron'  'Cu K\a' 'synchrotron'
    _definition
;              Description of the radiation used to measure the unit-cell data.
               See also  _cell_measurement_wavelength.
;

data_cell_measurement_reflns_used
    _name                      '_cell_measurement_reflns_used'
    _category                    cell
    _type                        numb
    _definition
;              The total number of reflections used to determine the unit cell.
               These reflections may be specified as _cell_measurement_refln_
               data items.
;

data_cell_measurement_temperature
    _name                      '_cell_measurement_temperature'
    _category                    cell
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _definition
;              The temperature in kelvins at which the unit-cell parameters
               were measured (not the temperature of synthesis).
;

data_cell_measurement_theta_
    loop_ _name                '_cell_measurement_theta_max'
                               '_cell_measurement_theta_min'
    _category                    cell
    _type                        numb
    _enumeration_range           0.0:90.0
    _units                       deg
    _units_detail              'degrees'
    _definition
;              The maximum and minimum theta angles of reflections
               used to measure the unit cell in degrees.
;

data_cell_measurement_wavelength
    _name                      '_cell_measurement_wavelength'
    _category                    cell
    _type                        numb
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The wavelength in angstroms of the radiation used to measure
               the unit cell. If this is not specified, the wavelength is
               assumed to be the same as that given in
               _diffrn_radiation_wavelength.
;
data_cell_reciprocal_angle_
    loop_ _name                '_cell_reciprocal_angle_alpha'
                               '_cell_reciprocal_angle_beta'
                               '_cell_reciprocal_angle_gamma'
    _category                    cell
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:180.0
    _enumeration_default         90.0
    _units                       deg
    _units_detail              'degrees'
    _definition
;              The angles defining the reciprocal cell in degrees. These
               are related to those in the real cell by:

               cos(recip-alpha)
                   = [cos(beta)*cos(gamma) - cos(alpha)]/[sin(beta)*sin(gamma)]

               cos(recip-beta)
                   = [cos(gamma)*cos(alpha) - cos(beta)]/[sin(gamma)*sin(alpha)]

               cos(recip-gamma)
                   = [cos(alpha)*cos(beta) - cos(gamma)]/[sin(alpha)*sin(beta)]

               Ref: Buerger, M. J. (1942). X-ray Crystallography, p. 360.
                       New York: John Wiley & Sons Inc.
;

data_cell_reciprocal_length_
    loop_ _name                '_cell_reciprocal_length_a'
                               '_cell_reciprocal_length_b'
                               '_cell_reciprocal_length_c'
    _category                    cell
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _units                       A^-1^
    _units_detail              'reciprocal angstroms'
    _definition
;              The reciprocal-cell lengths in inverse angstroms.  These are
               related to the real cell by:

               recip-a = b*c*sin(alpha)/V

               recip-b = c*a*sin(beta)/V

               recip-c = a*b*sin(gamma)/V

               where V is the cell volume.

               Ref: Buerger, M. J. (1942). X-ray Crystallography, p. 360.
                       New York: John Wiley & Sons Inc.
;

data_cell_special_details
    _name                      '_cell_special_details'
    _category                    cell
    _type                        char
    loop_ _example              'pseudo-orthorhombic'
                                'standard setting from 45 deg rotation around c'
    _definition
;              A description of special aspects of the cell choice, noting
               possible alternative settings.
;

data_cell_volume
    _name                      '_cell_volume'
    _category                    cell
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _units                       A^3^
    _units_detail              'cubic angstroms'
    _definition
;              Cell volume V in angstroms cubed.

               V = a b c [1 - cos^2^(alpha) - cos^2^(beta) - cos^2^(gamma)
                           + 2 cos(alpha) cos(beta) cos(gamma) ] ^1/2^

               a     = _cell_length_a
               b     = _cell_length_b
               c     = _cell_length_c
               alpha = _cell_angle_alpha
               beta  = _cell_angle_beta
               gamma = _cell_angle_gamma
;

############################
## CELL_MEASUREMENT_REFLN ##
############################

data_cell_measurement_refln_[]
    _name                      '_cell_measurement_refln_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
     _cell_measurement_refln_index_h
     _cell_measurement_refln_index_k
     _cell_measurement_refln_index_l
     _cell_measurement_refln_theta
       -2    4    1          8.67
        0    3    2          9.45
        3    0    2          9.46
       -3    4    1          8.93
       -2    1   -2          7.53
       10    0    0         23.77
        0   10    0         23.78
       -5    4    1         11.14
      # - - - - data truncated for brevity - - - -
;
;
    Example 1 - extracted from the CAD-4 listing for Rb~2~S~2~O~6~ at room
                temperature (unpublished).
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the CELL_MEASUREMENT_REFLN category record
               details about the reflections used in the determination of the
               crystallographic cell parameters.

               The _cell_measurement_refln_ data items would in general be used
               only for diffractometer measurements.
;

data_cell_measurement_refln_index_
    loop_ _name                '_cell_measurement_refln_index_h'
                               '_cell_measurement_refln_index_k'
                               '_cell_measurement_refln_index_l'
    _category                    cell_measurement_refln
    _type                        numb
    _list                        yes
    _list_mandatory              yes
    _definition
;              Miller indices of a reflection used for measurement of
               the unit cell.
;

data_cell_measurement_refln_theta
    _name                      '_cell_measurement_refln_theta'
    _category                    cell_measurement_refln
    _type                        numb
    _list                        yes
    _list_reference            '_cell_measurement_refln_index_'
    _enumeration_range           0.0:90.0
    _units                       deg
    _units_detail              'degrees'
    _definition
;              Theta angle in degrees for the reflection used for
               measurement of the unit cell with the indices
               _cell_measurement_refln_index_.
;

##############
## CHEMICAL ##
##############

data_chemical_[]
    _name                      '_chemical_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _chemical_name_systematic
      trans-bis(tricyclohexylphosphine)tetracarbonylmolybdenum(0)
;
;
    Example 1 - based on data set 9597gaus of Alyea, Ferguson & Kannan
                [Acta Cryst. (1996), C52, 765-767].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the CHEMICAL category record details about the
               composition and chemical properties of the compound. The
               formula data items must agree with those that specify the
               density, unit-cell and Z values.
;

data_chemical_absolute_configuration
    _name                      '_chemical_absolute_configuration'
    _category                    chemical
    _type                        char
    loop_ _enumeration
          _enumeration_detail    rm
;                                        Absolute configuration established by
                                         the structure determination of a
                                         compound containing a chiral reference
                                         molecule of known absolute
                                         configuration.
;
                                 ad
;                                        Absolute configuration established by
                                         anomalous-dispersion effects in
                                         diffraction measurements on the
                                         crystal.
;
                                 rmad
;                                        Absolute configuration established by
                                         the structure determination of a
                                         compound containing a chiral reference
                                         molecule of known absolute
                                         configuration and confirmed by
                                         anomalous-dispersion effects in
                                         diffraction measurements on the
                                         crystal.
;
                                 syn
;                                        Absolute configuration has not been
                                         established by anomalous-dispersion
                                         effects in diffraction measurements on
                                         the crystal. The enantiomer has been
                                         assigned by reference to an unchanging
                                         chiral centre in the synthetic
                                         procedure.
;
                                 unk
;                                        Absolute configuration is unknown,
                                         there being no firm chemical evidence
                                         for its assignment to hand and it
                                         having not been established by
                                         anomalous-dispersion effects in
                                         diffraction measurements on the
                                         crystal. An arbitrary choice of
                                         enantiomer has been made.
;
                                 .      'Inapplicable.'
    _definition
;              Necessary conditions for the assignment of
               _chemical_absolute_configuration are given by H. D. Flack and
               G. Bernardinelli (1999, 2000).

               Ref: Flack, H. D. & Bernardinelli, G. (1999). Acta Cryst. A55,
                       908-915. (http://www.iucr.org/paper?sh0129)
                    Flack, H. D. & Bernardinelli, G. (2000). J. Appl. Cryst.
                       33, 1143-1148. (http://www.iucr.org/paper?ks0021)
;

data_chemical_compound_source
    _name                      '_chemical_compound_source'
    _category                    chemical
    _type                        char
    loop_ _example              'From Norilsk (USSR)'
                                'Extracted from the bark of Cinchona Naturalis'
    _definition
;              Description of the source of the compound under study, or of the
               parent  molecule if a simple derivative is studied. This includes
               the place of  discovery for minerals or the actual source of a
               natural product.
;

data_chemical_enantioexcess_bulk
    _name                      '_chemical_enantioexcess_bulk'
    _category                    chemical
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:1.0
    _units                       .
    _units_detail                dimensionless
    _definition
;              The enantioexcess of the bulk material from which the 
               crystals were grown. A value of 0.0 indicates the
               racemate. A value of 1.0 indicates that the compound
               is enantiomerically pure.

               Enantioexcess is defined in the IUPAC Recommendations
               (Moss et al., 1996). The composition of the crystal
               and bulk must be the same.

               Ref: Moss G. P. et al. (1996). Basic Terminology of
                    Stereochemistry. Pure Appl. Chem., 68, 2193-2222.
                    http://www.chem.qmul.ac.uk/iupac/stereo/index.html 
;

data_chemical_enantioexcess_bulk_technique
    _name                      '_chemical_enantioexcess_bulk_technique'
    _category                    chemical
    _type                        char
    loop_ _enumeration
          _enumeration_detail    OA
;                                     Enantioexcess determined by
                                      measurement of the specific rotation
                                      of the optical activity of the bulk
                                      compound in solution.
;
                                 CD
;                                     Enantioexcess determined by
                                      measurement of the visible/near UV
                                      circular dichroism spectrum of the
                                      bulk compound in solution.
;
                                 EC
;                                     Enantioexcess determined by
                                      enantioselective chromatography of
                                      the bulk compound in solution.
;
                                 other
;                                     Enantioexcess determined by 
                                      a technique not included elsewhere
                                      in this list.
;
    _definition
;              The experimental technique used to determine the
               enantioexcess of the bulk compound.
;

data_chemical_enantioexcess_crystal
    _name                      '_chemical_enantioexcess_crystal'
    _category                    chemical
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:1.0
    _units                       .
    _units_detail                dimensionless
    _definition
;              The enantioexcess of the crystal used for the diffraction
               study. A value of 0.0 indicates the racemate. A value of
               1.0 indicates that the crystal is enantiomerically pure.

               Enantioexcess is defined in the IUPAC Recommendations
               (Moss et al., 1996).

               Ref: Moss G. P. et al. (1996). Basic Terminology of
                    Stereochemistry. Pure Appl. Chem., 68, 2193-2222.
                    http://www.chem.qmul.ac.uk/iupac/stereo/index.html 
;


data_chemical_enantioexcess_crystal_technique
    _name                      '_chemical_enantioexcess_crystal_technique'
    _category                    chemical
    _type                        char
    loop_ _enumeration
          _enumeration_detail    CD
;                                     Enantioexcess determined by
                                      measurement of the visible/near UV
                                      circular dichroism spectrum of the
                                      crystal taken into solution.
;
                                 EC
;                                     Enantioexcess determined by
                                      enantioselective chromatography of
                                      the crystal taken into solution.
;
                                 other
;                                     Enantioexcess determined by 
                                      a technique not included elsewhere
                                      in this list.
;
    _definition
;              The experimental technique used to determine the
               enantioexcess of the crystal.
;

data_chemical_melting_point
    _name                      '_chemical_melting_point'
    _category                    chemical
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _definition
;              The temperature in kelvins at which the crystalline solid changes
               to a liquid.
;

data_chemical_melting_point_
    loop_  _name               '_chemical_melting_point_gt'
                               '_chemical_melting_point_lt'
    _category                    chemical
    _type                        numb
    _related_item              '_chemical_melting_point'
    _related_function            alternate
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _definition
;              A temperature in kelvins below which (*_lt) or above
               which (*_gt) the melting point (the temperature at which the
               crystalline solid changes to a liquid) lies. These items allow a
               range of temperatures to be given.

               _chemical_melting_point should always be used in preference
               to these items whenever possible.
;

data_chemical_name_common
    _name                      '_chemical_name_common'
    _category                    chemical
    _type                        char
    _example                    '1-bromoestradiol'
    _definition
;              Trivial name by which the compound is commonly known.
;

data_chemical_name_mineral
    _name                      '_chemical_name_mineral'
    _category                    chemical
    _type                        char
    _example                     chalcopyrite
    _definition
;              Mineral name accepted by the International Mineralogical
               Association. Use only for natural minerals. See also
               _chemical_compound_source.
;

data_chemical_name_structure_type
    _name                      '_chemical_name_structure_type'
    _category                    chemical
    _type                        char
    loop_ _example               perovskite   sphalerite    A15
    _definition
;              Commonly used structure-type name. Usually only applied to
               minerals or inorganic compounds.
;

data_chemical_name_systematic
    _name                      '_chemical_name_systematic'
    _category                    chemical
    _type                        char
    _example                    '1-bromoestra-1,3,5(10)-triene-3,17\b-diol'
    _definition
;              IUPAC or Chemical Abstracts full name of the compound.
;

data_chemical_optical_rotation
    _name                      '_chemical_optical_rotation'
    _category                    chemical
    _type                        char
    _example                   '[\a]^25^~D~ = +108 (c = 3.42, CHCl~3~)'
    _definition
;              The optical rotation in solution of the compound is
               specified in the following format:
                    '[\a]^TEMP^~WAVE~ = SORT (c = CONC, SOLV)'
               where:
                 TEMP is the temperature of the measurement in degrees
                      Celsius,
                 WAVE is an indication of the wavelength of the light
                      used for the measurement,
                 CONC is the concentration of the solution given as the
                      mass of the substance in g per 100 ml of solution,
                 SORT is the signed value (preceded by a + or a - sign)
                      of 100.\a/(l.c), where \a is the signed optical
                      rotation in degrees measured in a cell of length l in
                      dm and c is the value of CONC as defined above, and
                 SOLV is the chemical formula of the solvent.
;

data_chemical_properties_biological
    _name                      '_chemical_properties_biological'
    _category                    chemical
    _type                        char
   loop_    _example
;              diverse biological activities including use as a
               laxative and strong antibacterial activity against
               S. aureus and weak activity against
               cyclooxygenase-1 (COX-1)
;

;              antibiotic activity against Bacillus subtilis
               (ATCC 6051) but no significant activity against
               Candida albicans (ATCC 14053), Aspergillus flavus
               (NRRL 6541) and Fusarium verticillioides (NRRL
               25457)
;

;              weakly potent lipoxygenase nonredox inhibitor
;

;              no influenza A virus sialidase inhibitory and
               plaque reduction activities
;

;              low toxicity against Drosophila melanogaster
;

    _definition
;              A free-text description of the biological properties of the
               material.
;

data_chemical_properties_physical
    _name                      '_chemical_properties_physical'
    _category                    chemical
    _type                        char
  loop_  _example                air-sensitive
                                 moisture-sensitive
                                 hygroscopic
                                 deliquescent
                                 oxygen-sensitive
                                 photo-sensitive
                                 pyrophoric
                                 semiconductor
                                 'ferromagnetic at low temperature'
                                 'paramagnetic and thermochromic'
    _definition
;              A free-text description of the physical properties of the
               material.
;

data_chemical_temperature_decomposition
    _name                      '_chemical_temperature_decomposition'
    _category                    chemical
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _example                     350
    _definition
;              The temperature in kelvins at which the solid decomposes.
;

data_chemical_temperature_decomposition_
    loop_ _name     '_chemical_temperature_decomposition_gt'
                    '_chemical_temperature_decomposition_lt'
    _category                   chemical
    _type                       numb
    _enumeration_range           0.0:
    _units                      K
    _units_detail               kelvin
    _related_item               '_chemical_temperature_decomposition'
    _related_function           alternate
    _example                    350
    _definition
;              A temperature in kelvins below which (*_lt) or above which
               (*_gt) the solid is known to decompose. These items allow
               a range of temperatures to be given.

               _chemical_temperature_decomposition should always be used in
               preference to these items whenever possible.
;

data_chemical_temperature_sublimation
    _name                      '_chemical_temperature_sublimation'
    _category                    chemical
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _example                     350
    _definition
;              The temperature in kelvins at which the solid sublimes.
;

data_chemical_temperature_sublimation_
    loop_ _name                '_chemical_temperature_sublimation_gt'
                               '_chemical_temperature_sublimation_lt'
    _category                    chemical
    _type                        numb
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _related_item              '_chemical_temperature_sublimation'
    _related_function            alternate
    _example                     350
    _definition
;             A temperature in kelvins below which (*_lt) or above which
              (*_gt) the solid is known to sublime. These items allow a
              range of temperatures to be given.

              _chemical_temperature_sublimation should always be used in
              preference to these items whenever possible.
;


########################
## CHEMICAL_CONN_ATOM ##
########################

data_chemical_conn_atom_[]
    _name                      '_chemical_conn_atom_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _chemical_conn_atom_number
    _chemical_conn_atom_type_symbol
    _chemical_conn_atom_display_x
    _chemical_conn_atom_display_y
    _chemical_conn_atom_NCA
    _chemical_conn_atom_NH
        1   S    .39  .81   1   0
        2   S    .39  .96   2   0
        3   N    .14  .88   3   0
        4   C    .33  .88   3   0
        5   C    .11  .96   2   2
        6   C    .03  .96   2   2
        7   C    .03  .80   2   2
        8   C    .11  .80   2   2
        9   S    .54  .81   1   0
        10  S    .54  .96   2   0
        11  N    .80  .88   3   0
        12  C    .60  .88   3   0
        13  C    .84  .96   2   2
        14  C    .91  .96   2   2
        15  C    .91  .80   2   2
        16  C    .84  .80   2   2
;
;
    Example 1 - based on data set DPTD of Yamin, Suwandi, Fun, Sivakumar &
                bin Shawkataly [Acta Cryst. (1996), C52, 951-953].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the _chemical_conn_atom_ and _chemical_conn_bond_
               categories record details about the two-dimensional (2D)
               chemical structure of the molecular species. They allow a 2D
               chemical diagram to be reconstructed for use in a publication or
               in a database search for structural and substructural
               relationships.

               The _chemical_conn_atom_ data items provide information about
               the chemical properties of the atoms in the structure. In cases
               where crystallographic and molecular symmetry elements coincide,
               they must also contain symmetry-generated atoms, so that the
               _chemical_conn_atom_ and _chemical_conn_bond_ data items will
               always describe a complete chemical entity.
;

data_chemical_conn_atom_charge
    _name                      '_chemical_conn_atom_charge'
    _category                    chemical_conn_atom
    _type                        numb
    _list                        yes
    _list_reference            '_chemical_conn_atom_type_symbol'
    _enumeration_range           -6:6
    _enumeration_default         0
    loop_ _example
          _example_detail        1  'for an ammonium nitrogen'
                                -1  'for a chloride ion'
    _definition
;               The net integer charge assigned to this atom. This is the
               formal charge assignment normally found in chemical diagrams.
;

data_chemical_conn_atom_display_
    loop_ _name                '_chemical_conn_atom_display_x'
                               '_chemical_conn_atom_display_y'
    _category                    chemical_conn_atom
    _type                        numb
    _list                        yes
    _list_reference            '_chemical_conn_atom_type_symbol'
    _enumeration_range           0.0:1.0
    _definition
;              The 2D Cartesian coordinates (x,y) of the position of this atom
               in a recognizable chemical diagram. The coordinate origin is at
               the lower left corner, the x axis is horizontal and the y axis is
               vertical. The coordinates must lie in the range 0.0 to 1.0. These
               coordinates can be obtained from projections of a suitable
               uncluttered view of the molecular structure.
;

data_chemical_conn_atom_NCA
    _name                      '_chemical_conn_atom_NCA'
    _category                    chemical_conn_atom
    _type                        numb
    _list                        yes
    _list_reference            '_chemical_conn_atom_type_symbol'
    _enumeration_range           0:
    _definition
;              The number of connected atoms excluding terminal hydrogen atoms.
;

data_chemical_conn_atom_NH
    _name                      '_chemical_conn_atom_NH'
    _category                    chemical_conn_atom
    _type                        numb
    _list                        yes
    _list_reference            '_chemical_conn_atom_type_symbol'
    _enumeration_range           0:
    _definition
;              The total number of hydrogen atoms attached to this atom,
               regardless of whether they are included in the refinement or
               the _atom_site_ list. This number will be the same as
               _atom_site_attached_hydrogens only if none of the hydrogen
               atoms appear in the _atom_site_ list.
;

data_chemical_conn_atom_number
    _name                      '_chemical_conn_atom_number'
    _category                    chemical_conn_atom
    _type                        numb
    _list                        yes
    loop_ _list_link_child     '_atom_site_chemical_conn_number'
                               '_chemical_conn_bond_atom_1'
                               '_chemical_conn_bond_atom_2'
    _list_reference            '_chemical_conn_atom_type_symbol'
    _enumeration_range           1:
    _definition
;              The chemical sequence number to be associated with this atom.
;

data_chemical_conn_atom_type_symbol
    _name                      '_chemical_conn_atom_type_symbol'
    _category                    chemical_conn_atom
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _definition
;              A code identifying the atom type. This code must match an
               _atom_type_symbol code in the _atom_type_ list or be a
               recognizable element symbol.
;

########################
## CHEMICAL_CONN_BOND ##
########################

data_chemical_conn_bond_[]
    _name                      '_chemical_conn_bond_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _chemical_conn_bond_atom_1
    _chemical_conn_bond_atom_2
    _chemical_conn_bond_type
       4     1     doub     4     3     sing
       4     2     sing     5     3     sing
       6     5     sing     7     6     sing
       8     7     sing     8     3     sing
       10    2     sing     12    9     doub
       12    11    sing     12    10    sing
       13    11    sing     14    13    sing
       15    14    sing     16    15    sing
       16    11    sing     17    5     sing
       18    5     sing     19    6     sing
       20    6     sing     21    7     sing
       22    7     sing     23    8     sing
       24    8     sing     25    13    sing
       26    13    sing     27    14    sing
       28    14    sing     29    15    sing
       30    15    sing     31    16    sing
       32    16    sing
;
;
    Example 1 - based on data set DPTD of Yamin, Suwandi, Fun, Sivakumar &
                bin Shawkataly [Acta Cryst. (1996), C52, 951-953].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the _chemical_conn_atom_ and _chemical_conn_bond_
               categories record details about the two-dimensional (2D)
               chemical structure of the molecular species. They allow a 2D
               chemical diagram to be reconstructed for use in a publication
               or in a database search for structural and substructural
               relationships.

               The _chemical_conn_bond_ data items specify the connections
               between the atoms in the _chemical_conn_atom_ list and the nature
               of the chemical bond between these atoms.
;

data_chemical_conn_bond_atom_
    loop_ _name                '_chemical_conn_bond_atom_1'
                               '_chemical_conn_bond_atom_2'
    _category                    chemical_conn_bond
    _type                        numb
    _list                        yes
    _list_link_parent          '_chemical_conn_atom_number'
    _enumeration_range           1:
    _definition
;              Atom numbers which must match with chemical sequence numbers
               specified as _chemical_conn_atom_number values. These link the
               bond connection to the chemical numbering and atom sites.
;

data_chemical_conn_bond_type
    _name                      '_chemical_conn_bond_type'
    _category                    chemical_conn_bond
    _type                        char
    _list                        yes
    _list_reference            '_chemical_conn_bond_atom_'
    loop_ _enumeration
          _enumeration_detail    sing    'single bond'
                                 doub    'double bond'
                                 trip    'triple bond'
                                 quad    'quadruple bond'
                                 arom    'aromatic bond'
                                 poly    'polymeric bond'
                                 delo    'delocalized double bond'
                                 pi      'pi bond'
    _enumeration_default         sing
    _definition
;              The chemical bond type associated with the connection between
               the two sites _chemical_conn_bond_atom_1 and *_2.
;

######################
## CHEMICAL_FORMULA ##
######################

data_chemical_formula_[]
    _name                       '_chemical_formula_[]'
    _category                     category_overview
    _type                         null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _chemical_formula_moiety            'C18 H25 N O3'
    _chemical_formula_sum               'C18 H25 N O3'
    _chemical_formula_weight            303.40
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _chemical_formula_iupac      '[Mo (C O)4 (C18 H33 P)2]'
    _chemical_formula_moiety     'C40 H66 Mo O4 P2'
    _chemical_formula_structural '((C O)4 (P (C6 H11)3)2)Mo'
    _chemical_formula_sum         'C40 H66 Mo O4 P2'
    _chemical_formula_weight      768.81
;
;
    Example 2 - based on data set 9597gaus of Alyea, Ferguson & Kannan
                [Acta Cryst. (1996), C52, 765-767].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              _chemical_formula_ items specify the composition and chemical
              properties of the compound. The formula data items must agree
              with those that specify the density, unit-cell and Z values.

              The following rules apply to the construction of the data items
              _chemical_formula_analytical, *_structural and *_sum. For the
              data item *_moiety, the formula construction is broken up into
              residues or moieties, i.e. groups of atoms that form a molecular
              unit or molecular ion. The  rules given below apply within each
              moiety but different requirements apply to the way that moieties
              are connected (see _chemical_formula_moiety).

              (1) Only recognized element symbols may be used.

              (2) Each element symbol is followed by a 'count' number. A
                 count of '1' may be omitted.

              (3) A space or parenthesis must separate each cluster of (element
                 symbol + count).

              (4) Where a group of elements is enclosed in parentheses, the
                 multiplier for the group must follow the closing parenthesis.
                 That is, all element and group multipliers are assumed to be
                 printed as subscripted numbers. (An exception to this rule
                 exists for *_moiety formulae where pre- and post-multipliers
                 are permitted for molecular units.)

              (5) Unless the elements are ordered in a manner that corresponds
                 to their chemical structure, as in
                 _chemical_formula_structural, the order of the elements within
                 any group or moiety depends on whether carbon is present or
                 not. If carbon is present, the order should be: C, then H,
                 then the other elements in alphabetical order of their
                 symbol. If carbon is not present, the elements are listed
                 purely in alphabetical order of their symbol. This is the
                 'Hill' system used by Chemical Abstracts. This ordering is
                 used in _chemical_formula_moiety and _chemical_formula_sum.
;

data_chemical_formula_analytical
    _name                      '_chemical_formula_analytical'
    _category                    chemical_formula
    _type                        char
    _example                    'Fe2.45(2)  Ni1.60(3)  S4'
    _definition
;              Formula determined by standard chemical analysis including trace
               elements. See the _chemical_formula_[] category description for 
               rules for writing chemical formulae. Parentheses are used only 
               for standard uncertainties (e.s.d.'s).
;

data_chemical_formula_iupac
    _name                      '_chemical_formula_iupac'
    _category                    chemical_formula
    _type                        char
    _example                    '[Co Re (C12 H22 P)2 (C O)6].0.5C H3 O H'
    _definition
;              Formula expressed in conformance with IUPAC rules for inorganic
               and metal-organic compounds where these conflict with the rules
               for any other _chemical_formula_ entries. Typically used for
               formatting a formula in accordance with journal rules. This
               should appear in the data block in addition to the most
               appropriate of the other _chemical_formula_ data names.

               Ref: IUPAC (1990). Nomenclature of Inorganic Chemistry.
                    Oxford: Blackwell Scientific Publications.
;

data_chemical_formula_moiety
    _name                      '_chemical_formula_moiety'
    _category                    chemical_formula
    _type                        char
    loop_ _example              'C7 H4 Cl Hg N O3 S'
                                'C12 H17 N4 O S 1+, C6 H2 N3 O7 1-'
                                'C12 H16 N2 O6, 5(H2 O1)'
                                "(Cd 2+)3, (C6 N6 Cr 3-)2, 2(H2 O)"
    _definition
;              Formula with each discrete bonded residue or ion shown as a
               separate moiety. See the _chemical_formula_[] category 
               description for rules for writing chemical formulae. In addition 
               to the general formulae requirements, the following rules apply:
                  (1) Moieties are separated by commas ','.
                  (2) The order of elements within a moiety follows general rule
                     (5) in the _chemical_formula_[] category description.
                  (3) Parentheses are not used within moieties but may surround
                     a moiety. Parentheses may not be nested.
                  (4) Charges should be placed at the end of the moiety. The
                     charge '+' or '-' may be preceded by a numerical multiplier
                     and should be separated from the last (element symbol +
                     count) by a space. Pre- or post-multipliers may be used for
                     individual moieties.
;

data_chemical_formula_structural
    _name                      '_chemical_formula_structural'
    _category                    chemical_formula
    _type                        char
    loop_ _example              'Ca ((Cl O3)2 O)2 (H2 O)6'
                                '(Pt (N H3)2 (C5 H7 N3 O)2) (Cl O4)2'
    _definition
;              See the _chemical_formula_[] category description for the rules 
               for writing chemical formulae for inorganics, organometallics, 
               metal complexes etc., in which  bonded groups are preserved 
               as discrete entities within parentheses, with post-multipliers
               as required. The order of the elements should give as much
               information as possible about the chemical structure.
               Parentheses may be used and nested as required. This formula
               should correspond to the structure as actually reported,
               i.e. trace elements not included in atom-type and atom-site
               lists should not be included in this formula (see also
               _chemical_formula_analytical).
;

data_chemical_formula_sum
    _name                      '_chemical_formula_sum'
    _category                    chemical_formula
    _type                        char
    loop_ _example              'C18 H19 N7 O8 S'
    _definition
;              See the _chemical_formula_[] category description for the rules 
               for writing chemical formulae in which all discrete bonded 
               residues and ions are summed over the constituent elements, 
               following the ordering given in general rule (5) in the 
               _chemical_formula_[] category description. Parentheses are not 
               normally used.
;

data_chemical_formula_weight
    _name                      '_chemical_formula_weight'
    _category                    chemical_formula
    _type                        numb
    _enumeration_range           1.0:
    _units                       Da
    _units_detail              'daltons'
    _definition
;              Formula mass in daltons. This mass should correspond to the
               formulae given under _chemical_formula_structural, *_iupac,
               *_moiety or *_sum and, together with the Z value and cell
               parameters, should yield the density given as
               _exptl_crystal_density_diffrn.
;

data_chemical_formula_weight_meas
    _name                      '_chemical_formula_weight_meas'
    _category                    chemical_formula
    _type                        numb
    _enumeration_range           1.0:
    _units                       Da
    _units_detail              'daltons'
    _definition
;              Formula mass in daltons measured by a non-diffraction experiment.
;

##############
## CITATION ##
##############

data_citation_[]
    _name                      '_citation_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _citation_id
    _citation_coordinate_linkage
    _citation_title
    _citation_country
    _citation_page_first
    _citation_page_last
    _citation_year
    _citation_journal_abbrev
    _citation_journal_volume
    _citation_journal_issue
    _citation_journal_id_ASTM
    _citation_journal_id_ISSN
    _citation_book_title
    _citation_book_publisher
    _citation_book_id_ISBN
    _citation_special_details
      primary  yes
    ; Crystallographic analysis of a complex between human
      immunodeficiency virus type 1 protease and
      acetyl-pepstatin at 2.0-Angstroms resolution.
    ;
      US  14209  14219  1990  'J. Biol. Chem.'  265  .
      HBCHA3  0021-9258  .  .  .
    ; The publication that directly relates to this coordinate
      set.
    ;
      2  no
    ; Three-dimensional structure of aspartyl-protease from
      human immunodeficiency virus HIV-1.
    ;
      UK  615  619  1989  'Nature'  337  .
      NATUAS  0028-0836  .  .  .
    ; Determination of the structure of the unliganded enzyme.
    ;
      3 no
    ; Crystallization of the aspartylprotease from human
      immunodeficiency virus, HIV-1.
    ;
      US  1919  1921  1989  'J. Biol. Chem.'  264  .
      HBCHA3  0021-9258  .  .  .
    ; Crystallization of the unliganded enzyme.
    ;
;
;
    Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the CITATION category record details about the
               literature cited as being relevant to the contents of the data
               block.
;

data_citation_abstract
    _name                      '_citation_abstract'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _definition
;              Abstract for the citation. This is used most when the
               citation is extracted from a bibliographic database that
               contains full text or abstract information.
;

data_citation_abstract_id_CAS
    _name                      '_citation_abstract_id_CAS'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _definition
;              The Chemical Abstracts Service (CAS) abstract identifier;
               relevant for journal articles.
;

data_citation_book_id_ISBN
    _name                      '_citation_book_id_ISBN'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _definition
;              The International Standard Book Number (ISBN) code assigned to
               the book cited;  relevant for books or book chapters.
;

data_citation_book_publisher
    _name                      '_citation_book_publisher'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _example                    'John Wiley'
    _definition
;              The name of the publisher of the citation; relevant
               for books or book chapters.
;

data_citation_book_publisher_city
    _name                      '_citation_book_publisher_city'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _example                    'New York'
    _definition
;              The location of the publisher of the citation; relevant
               for books or book chapters.
;

data_citation_book_title
    _name                      '_citation_book_title'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _definition
;              The title of the book in which the citation appeared;  relevant
               for books or book chapters.
;

data_citation_coordinate_linkage
    _name                      '_citation_coordinate_linkage'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    loop_ _enumeration
          _enumeration_detail    no  'citation unrelated to current coordinates'
                                 n   'abbreviation for "no"'
                                 yes 'citation related to current coordinates'
                                 y   'abbreviation for "yes"'
    _definition
;              _citation_coordinate_linkage states whether or not this citation
               is concerned with precisely the set of coordinates given in the
               data block. If, for instance, the publication described the same
               structure, but the coordinates had undergone further refinement
               prior to creation of the data block, the value of this data item
               would be 'no'.
;

data_citation_country
    _name                      '_citation_country'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _definition
;              The country of publication;  relevant for books and book
               chapters.
;

data_citation_database_id_CSD
    _name                      '_citation_database_id_CSD'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _example                     LEKKUH
    _definition
;           Identifier ('refcode') of the database record in the Cambridge
            Structural Database that contains details of the cited structure.
;

data_citation_database_id_Medline
    _name                      '_citation_database_id_Medline'
    _category                    citation
    _type                        numb
    _list                        yes
    _list_reference            '_citation_id'
    _enumeration_range           1:
    _example                     89064067
    _definition
;              Accession number used by Medline to categorize a specific
               bibliographic entry.
;

data_citation_id
    _name                      '_citation_id'
    _category                    citation
    _type                        char
    _list                        yes
    _list_mandatory              yes
    loop_ _list_link_child     '_citation_author_citation_id'
                               '_citation_editor_citation_id'
    loop_ _example               primary  1  2  3
    _definition
;              The value of _citation_id must uniquely identify a record in the
               _citation_ list.

               The _citation_id 'primary' should be used to indicate the
               citation that the author(s) consider to be the most pertinent to
               the contents of the data block.

               Note that this item need not be a number;  it can be any unique
               identifier.
;

data_citation_journal_abbrev
    _name                      '_citation_journal_abbrev'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _example                    'J. Mol. Biol.'
    _definition
;              Abbreviated name of the journal cited as given in the Chemical
               Abstracts Service Source Index.
;

data_citation_journal_full
    _name                      '_citation_journal_full'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _example                    'Journal of Molecular Biology'
    _definition
;              Full name of the journal cited; relevant for journal articles.
;

data_citation_journal_id_ASTM
    _name                      '_citation_journal_id_ASTM'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _definition
;              The American Society for Testing and Materials (ASTM) code
               assigned to the journal cited (also referred to as the CODEN
               designator of the Chemical Abstracts Service); relevant for
               journal articles.
;

data_citation_journal_id_CSD
    _name                      '_citation_journal_id_CSD'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _example                    '0070'
    _definition
;              The Cambridge Structural Database (CSD) code assigned to the
               journal cited; relevant for journal articles. This is also the
               system used at the Protein Data Bank (PDB).
;

data_citation_journal_id_ISSN
    _name                      '_citation_journal_id_ISSN'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _definition
;              The International Standard Serial Number (ISSN) code assigned to
               the journal cited;  relevant for journal articles.
;

data_citation_journal_issue
    _name                      '_citation_journal_issue'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _example                     2
    _definition
;              Issue number of the journal cited;  relevant for journal
               articles.
;

data_citation_journal_volume
    _name                      '_citation_journal_volume'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _example                     174
    _definition
;              Volume number of the journal cited;  relevant for journal
               articles.
;

data_citation_language
    _name                      '_citation_language'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _example                     German
    _definition
;              Language in which the cited article is written.
;

data_citation_page_
    loop_ _name                '_citation_page_first'
                               '_citation_page_last'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _definition
;              The first and last pages of the citation;  relevant for
               journal articles, books and book chapters.
;

data_citation_special_details
    _name                      '_citation_special_details'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    loop_ _example
;                       citation relates to this precise coordinate set
;
;                       citation relates to earlier low-resolution structure
;
;                       citation relates to further refinement of structure
                        reported in citation 2
;
    _definition
;              A description of special aspects of the relationship
               of the contents of the data block to the literature item cited.
;

data_citation_title
    _name                      '_citation_title'
    _category                    citation
    _type                        char
    _list                        yes
    _list_reference            '_citation_id'
    _example
;                       Structure of diferric duck ovotransferrin at 2.35 \%A
                        resolution.
;
    _definition
;              The title of the citation;  relevant for journal articles, books
               and book chapters.
;

data_citation_year
    _name                      '_citation_year'
    _category                    citation
    _type                        numb
    _list                        yes
    _list_reference            '_citation_id'
    _example                     1984
    _definition
;              The year of the citation;  relevant for journal articles, books
               and book chapters.
;

#####################
## CITATION_AUTHOR ##
#####################

data_citation_author_[]
    _name                      '_citation_author_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _citation_author_citation_id
    _citation_author_name
      primary  'Fitzgerald, P.M.D.'
      primary  'McKeever, B.M.'
      primary  'Van Middlesworth, J.F.'
      primary  'Springer, J.P.'
      primary  'Heimbach, J.C.'
      primary  'Leu, C.-T.'
      primary  'Herber, W.K.'
      primary  'Dixon, R.A.F.'
      primary  'Darke, P.L.'
      2        'Navia, M.A.'
      2        'Fitzgerald, P.M.D.'
      2        'McKeever, B.M.'
      2        'Leu, C.-T.'
      2        'Heimbach, J.C.'
      2        'Herber, W.K.'
      2        'Sigal, I.S.'
      2        'Darke, P.L.'
      2        'Springer, J.P.'
      3        'McKeever, B.M.'
      3        'Navia, M.A.'
      3        'Fitzgerald, P.M.D.'
      3        'Springer, J.P.'
      3        'Leu, C.-T.'
      3        'Heimbach, J.C.'
      3        'Herber, W.K.'
      3        'Sigal, I.S.'
      3        'Darke, P.L.'
;
;
    Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the CITATION_AUTHOR category record details
               about the authors associated with the citations in the
               _citation_ list.
;

data_citation_author_citation_id
    _name                      '_citation_author_citation_id'
    _category                    citation_author
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_parent          '_citation_id'
    _definition
;              The value of _citation_author_citation_id must match an
               identifier specified by _citation_id in the _citation_ list.
;

data_citation_author_name
    _name                      '_citation_author_name'
    _category                    citation_author
    _type                        char
    _list                        yes
    _list_mandatory              yes
    loop_ _example             'Bleary, Percival R.'
                               "O'Neil, F.K."
                               'Van den Bossche, G.'
                               'Yang, D.-L.'
                               'Simonov, Yu.A.'
                               'M\"uller, H.A.'
                               'Ross II, C.R.'
    _definition
;              Name of an author of the citation; relevant for journal
               articles, books and book chapters.

               The family name(s), followed by a comma and including any
               dynastic components, precedes the first name(s) or initial(s).
;

data_citation_author_ordinal
    _name                      '_citation_author_ordinal'
    _category                    citation_author
    _type                        char
    _list                        yes
    _definition
;              This data name defines the order of the author's name in the
               list of authors of a citation.
;

#####################
## CITATION_EDITOR ##
#####################

data_citation_editor_[]
    _name                      '_citation_editor_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _citation_editor_citation_id
    _citation_editor_name
      5        'McKeever, B.M.'
      5        'Navia, M.A.'
      5        'Fitzgerald, P.M.D.'
      5        'Springer, J.P.'
;
;
    Example 1 - hypothetical example.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the CITATION_EDITOR category record details
               about the editor associated with the book or book chapter
               citations in the _citation_ list.
;

data_citation_editor_citation_id
    _name                      '_citation_editor_citation_id'
    _category                    citation_editor
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_parent          '_citation_id'
    _definition
;              The value of _citation_editor_citation_id must match an
               identifier specified by _citation_id in the _citation_ list.
;

data_citation_editor_name
    _name                      '_citation_editor_name'
    _category                    citation_editor
    _type                        char
    _list                        yes
    _list_mandatory              yes
    loop_ _example             'Bleary, Percival R.'
                               "O'Neil, F.K."
                               'Van den Bossche, G.'
                               'Yang, D.-L.'
                               'Simonov, Yu.A.'
                               'M\"uller, H.A.'
                               'Ross II, C.R.'
    _definition
;              Name of an editor of the citation;  relevant for books and
               book chapters.

               The family name(s), followed by a comma and including any
               dynastic components, precedes the first name(s) or initial(s).
;

data_citation_editor_ordinal
    _name                      '_citation_editor_ordinal'
    _category                    citation_editor
    _type                        char
    _list                        yes
    _definition
;              This data name defines the order of the editor's name in the
               list of editors of a citation.
;

###############
## COMPUTING ##
###############

data_computing_[]
    _name                      '_computing_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _computing_data_collection       'CAD-4 (Enraf-Nonius, 1989)'
    _computing_cell_refinement       'CAD-4 (Enraf-Nonius, 1989)'
    _computing_data_reduction        'CFEO (Solans, 1978)'
    _computing_structure_solution    'SHELXS86 (Sheldrick, 1990)'
    _computing_structure_refinement  'SHELXL93 (Sheldrick, 1993)'
    _computing_molecular_graphics    'ORTEPII (Johnson, 1976)'
    _computing_publication_material  'PARST (Nardelli, 1983)'
;
;
    Example 1 - Rodr\'iguez-Romero, Ruiz-P\'erez & Solans
                [Acta Cryst. (1996), C52, 1415-1417].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the COMPUTING category record details about the
               computer programs used in the crystal structure analysis.
;

data_computing_
    loop_ _name                '_computing_cell_refinement'
                               '_computing_data_collection'
                               '_computing_data_reduction'
                               '_computing_molecular_graphics'
                               '_computing_publication_material'
                               '_computing_structure_refinement'
                               '_computing_structure_solution'
    _category                    computing
    _type                        char
    loop_ _example              'CAD-4 (Enraf-Nonius, 1989)'
                                'DIFDAT, SORTRF, ADDREF (Hall & Stewart, 1990)'
                                'FRODO (Jones, 1986), ORTEP (Johnson, 1965)'
                                'CRYSTALS (Watkin, 1988)'
                                'SHELX85 (Sheldrick, 1985)'
    _definition
;              Software used in the processing of the data. Give the program
               or package name and a brief reference.
;

##############
## DATABASE ##
##############

data_database_[]
    _name                      '_database_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _database_code_CSD                  'VOBYUG'
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DATABASE category record details about the
               database identifiers of the data block.

               These data items are assigned by database managers and should
               only appear in a CIF if they originate from that source.
;

data_database_code_
    loop_ _name                '_database_code_CAS'
                               '_database_code_CSD'
                               '_database_code_ICSD'
                               '_database_code_MDF'
                               '_database_code_NBS'
                               '_database_code_PDB'
                               '_database_code_PDF'
    _category                    database
    _type                        char
    _definition
;              The codes are assigned by databases: Chemical Abstracts;
               Cambridge Structural Database (organic and metal-organic
               compounds); Inorganic Crystal Structure Database; Metals
               Data File (metal structures); NBS (NIST) Crystal Data
               Database (lattice parameters); Protein Data Bank; and the
               Powder Diffraction File (JCPDS/ICDD).
;

data_database_code_depnum_ccdc_archive
    _name                      '_database_code_depnum_ccdc_archive'
    _category                    database
    _type                        char
    _definition
;              Deposition numbers assigned by the Cambridge Crystallographic
               Data Centre (CCDC) to files containing structural information
               archived by the CCDC.
;

data_database_code_depnum_ccdc_fiz
    _name                      '_database_code_depnum_ccdc_fiz'
    _category                    database
    _type                        char
    _definition
;              Deposition numbers assigned by the Fachinformationszentrum
               Karlsruhe (FIZ) to files containing structural information
               archived by the Cambridge Crystallographic Data Centre (CCDC).
;

data_database_code_depnum_ccdc_journal
    _name                      '_database_code_depnum_ccdc_journal'
    _category                    database
    _type                        char
    _definition
;              Deposition numbers assigned by various journals to files
               containing structural information archived by the Cambridge
               Crystallographic Data Centre (CCDC).
;

data_database_CSD_history
    _name                      '_database_CSD_history'
    _category                    database
    _type                        char
    _definition
;              A history of changes made by the Cambridge Crystallographic Data
               Centre and incorporated into the Cambridge Structural Database
               (CSD).
;

data_database_journal_
    loop_ _name                '_database_journal_ASTM'
                               '_database_journal_CSD'
    _category                    database
    _type                        char
    _definition
;              The ASTM CODEN designator for a journal as given in the
               Chemical Source List maintained by the Chemical Abstracts
               Service, and the journal code used in the Cambridge Structural
               Database.
;

############
## DIFFRN ##
############

data_diffrn_[]
    _name                      '_diffrn_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _diffrn_special_details
    ; \q scan width (1.0 + 0.14tan\q)\%, \q scan rate
      1.2\% min^-1^. Background counts for 5 s on each side
      every scan.
    ;

    _diffrn_ambient_temperature         293
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN category record details about the
               intensity measurements.
;

data_diffrn_ambient_environment
    _name                      '_diffrn_ambient_environment'
    _category                    diffrn
    _type                        char
    loop_ _example               He      vacuum     'mother liquor'
    _definition
;              The gas or liquid surrounding the sample, if not air.
;

data_diffrn_ambient_pressure
    _name                      '_diffrn_ambient_pressure'
    _category                    diffrn
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _units                       kPa
    _units_detail               'kilopascals'
    _definition
;              The mean hydrostatic pressure in kilopascals at which the
               intensities were measured.
;

data_diffrn_ambient_pressure_
    loop_ _name                '_diffrn_ambient_pressure_gt'
                               '_diffrn_ambient_pressure_lt'
    _category                    diffrn
    _type                        numb
    _related_item              '_diffrn_ambient_pressure'
    _related_function            alternate
    _enumeration_range           0.0:
    _units                       kPa
    _units_detail             'kilopascals'
    _definition
;              The mean hydrostatic pressure in kilopascals above which (*_gt)
               or below which (*_lt) the intensities were measured. These
               items allow for a pressure range to be given.

               _diffrn_ambient_pressure should always be used in
               preference to these items whenever possible.
;

data_diffrn_ambient_temperature
    _name                      '_diffrn_ambient_temperature'
    _category                    diffrn
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _definition
;             The mean temperature in kelvins at which the intensities
              were measured.
;

data_diffrn_ambient_temperature_
    loop_  _name               '_diffrn_ambient_temperature_gt'
                               '_diffrn_ambient_temperature_lt'
    _category                    diffrn
    _type                        numb
    _related_item              '_diffrn_ambient_temperature'
    _related_function            alternate
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _definition
;             The mean temperature in kelvins above which (*_gt) or below
              which (*_lt) the intensities were measured.  These items allow
              a range of temperatures to be given.

              _diffrn_ambient_temperature should always be used in preference
              to these items whenever possible.
;

data_diffrn_crystal_treatment
    _name                      '_diffrn_crystal_treatment'
    _category                    diffrn
    _type                        char
    loop_ _example             'equilibrated in hutch for 24 hours'
                               'flash frozen in liquid nitrogen'
                               'slow cooled with direct air stream'
    _definition
;              Remarks about how the crystal was treated prior to the intensity
               measurements. Particularly relevant when intensities were
               measured at low temperature.
;

data_diffrn_measured_fraction_theta_full
     _name               '_diffrn_measured_fraction_theta_full'
     _category             diffrn
     _type                 numb
     _enumeration_range    0:1.0
     _definition
;         Fraction of unique (symmetry-independent) reflections measured
          out to _diffrn_reflns_theta_full.
;

data_diffrn_measured_fraction_theta_max
     _name               '_diffrn_measured_fraction_theta_max'
     _category             diffrn
     _type                 numb
     _enumeration_range    0:1.0
     _definition
;         Fraction of unique (symmetry-independent) reflections measured
          out to _diffrn_reflns_theta_max.
;

data_diffrn_special_details
    _name                      '_diffrn_special_details'
    _category                    diffrn
    _type                        char
    _example
;              The results may not be entirely reliable
               as the measurement was made during a heat
               wave when the air-conditioning had failed.
;
    _definition
;              Special details of the intensity-measurement process. Should
               include information about source instability, crystal motion,
               degradation and so on.
;

data_diffrn_symmetry_description
    _name                      '_diffrn_symmetry_description'
    _category                    diffrn
    _type                        char
    _definition
;              Observed diffraction point symmetry, systematic absences and
               possible space group(s) or superspace group(s) compatible with
               these.
;

#######################
## DIFFRN_ATTENUATOR ##
#######################

data_diffrn_attenuator_[]
    _name                      '_diffrn_attenuator_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
      loop_
        _diffrn_attenuator_code
        _diffrn_attenuator_scale       
            0         1.00
            1        16.97
            2        33.89
;
;
    Example 1 - hypothetical example.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_ATTENUATOR category record details
               about the diffraction attenuator scales employed.
;

data_diffrn_attenuator_code
    _name                      '_diffrn_attenuator_code'
    _category                    diffrn_attenuator
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_child           '_diffrn_refln_attenuator_code'
    _definition
;              A code associated with a particular attenuator setting. This code
               is referenced by the _diffrn_refln_attenuator_code which is
               stored with the intensities. See _diffrn_attenuator_scale.
;

data_diffrn_attenuator_material
    _name                      '_diffrn_attenuator_material'
    _category                    diffrn_attenuator
    _type                        char
    _list                        yes
    _list_reference            '_diffrn_attenuator_code'
    _definition
;              Material from which the attenuator is made.
;

data_diffrn_attenuator_scale
    _name                      '_diffrn_attenuator_scale'
    _category                    diffrn_attenuator
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_attenuator_code'
    _enumeration_range           1.0:
    _definition
;               The scale factor applied when an intensity measurement is
                reduced by an attenuator identified by _diffrn_attenuator_code.
                The measured intensity must be multiplied by this scale to
                convert it to the same scale as unattenuated intensities.
;

#####################
## DIFFRN_DETECTOR ##
#####################

data_diffrn_detector_[]
    _name                      '_diffrn_detector_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _diffrn_detector                    'multiwire'
    _diffrn_detector_type               'Siemens'
;
;
    Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_DETECTOR category describe the
               detector used to measure the scattered radiation, including
               any analyser and post-sample collimation.
;

data_diffrn_detector
    _name                      '_diffrn_detector'
    _category                    diffrn_detector
    _type                        char
    _related_item              '_diffrn_radiation_detector'
    _related_function            alternate
    loop_
    _example                   'photographic film'
                               'scintillation counter'
                               'CCD plate'
                               'BF~3~ counter'
    _definition
;              The general class of the radiation detector.
;

data_diffrn_detector_area_resol_mean
    _name                      '_diffrn_detector_area_resol_mean'
    _category                    diffrn_detector
    _type                        numb
    _enumeration_range           0.0:
    _units                       mm^-1^
    _units_detail              'pixels per millimetre'
    _definition
;              The resolution of an area detector, in pixels/mm.
;

data_diffrn_detector_details
    _name                      '_diffrn_detector_details'
    _category                    diffrn_detector
    _type                        char
    _definition
;              A description of special aspects of the radiation detector.
;

data_diffrn_detector_dtime
    _name                      '_diffrn_detector_dtime'
    _category                    diffrn_detector
    _related_item              '_diffrn_radiation_detector_dtime'
    _related_function            alternate
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              The deadtime in microseconds of the detector used to measure
               the diffraction intensities.
;

data_diffrn_detector_type
    _name                      '_diffrn_detector_type'
    _category                    diffrn_detector
    _type                        char
    _definition
;              The make, model or name of the detector device used.
;

data_diffrn_radiation_detector
    _name                      '_diffrn_radiation_detector'
    _category                    diffrn_detector
    _type                        char
    _related_item              '_diffrn_detector'
    _related_function            replace
    _definition
;              The detector used to measure the diffraction intensities.
;

data_diffrn_radiation_detector_dtime
    _name                      '_diffrn_radiation_detector_dtime'
    _category                    diffrn_detector
    _type                        numb
    _enumeration_range           0.0:
    _related_item              '_diffrn_detector_dtime'
    _related_function            replace
    _definition
;              The deadtime in microseconds of the detector used to measure
               the diffraction intensities.
;

########################
## DIFFRN_MEASUREMENT ##
########################

data_diffrn_measurement_[]
    _name                      '_diffrn_measurement_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _diffrn_measurement_device_type
                              'Philips PW1100/20 diffractometer'
    _diffrn_measurement_method          \q/2\q
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_MEASUREMENT category refer to the
               mounting of the sample and to the goniometer on which it is
               mounted.
;

data_diffrn_measurement_details
    _name                      '_diffrn_measurement_details'
    _category                    diffrn_measurement
    _type                        char
    _example                   '440 frames of 0.25\%'
    _definition
;              A description of special aspects of the intensity measurement.
;

data_diffrn_measurement_device
    _name                      '_diffrn_measurement_device'
    _category                    diffrn_measurement
    _type                        char
    loop_
    _example                    'three-circle diffractometer'
                                'four-circle diffractometer'
                                '\k-geometry diffractometer'
                                'oscillation camera'
                                'precession camera'
    _definition
;              The general class of goniometer or device used to support
               and orient the specimen.
;

data_diffrn_measurement_device_details
    _name                      '_diffrn_measurement_device_details'
    _category                    diffrn_measurement
    _type                        char
    _example
;                                commercial goniometer modified locally to
                                 allow for 90\% \t arc
;
    _definition
;              A description of special aspects of the device used to measure
               the diffraction intensities.
;

data_diffrn_measurement_device_type
    _name                      '_diffrn_measurement_device_type'
    _category                    diffrn_measurement
    _type                        char
    _definition
;              The make, model or name of the measurement device
               (goniometer) used.
;

data_diffrn_measurement_method
    _name                      '_diffrn_measurement_method'
    _category                    diffrn_measurement
    _type                        char
    _example                    'profile data from \q/2\q scans'
    _definition
;              Method used to measure the intensities.
;

data_diffrn_measurement_specimen_support
    _name                      '_diffrn_measurement_specimen_support'
    _category                    diffrn_measurement
    _type                        char
    loop_ _example             'glass capillary'
                               'quartz capillary'
                               'fiber'
                               'metal loop'
    _definition
;              The physical device used to support the crystal during data
               collection.
;

##########################
## DIFFRN_ORIENT_MATRIX ##
##########################

data_diffrn_orient_matrix_[]
    _name                      '_diffrn_orient_matrix_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _diffrn_orient_matrix_UB_11           -0.04170
    _diffrn_orient_matrix_UB_12           -0.01429
    _diffrn_orient_matrix_UB_13           -0.02226
    _diffrn_orient_matrix_UB_21           -0.00380
    _diffrn_orient_matrix_UB_22           -0.05578
    _diffrn_orient_matrix_UB_23           -0.05048
    _diffrn_orient_matrix_UB_31            0.00587
    _diffrn_orient_matrix_UB_32           -0.13766
    _diffrn_orient_matrix_UB_33            0.02277

    _diffrn_orient_matrix_type 'TEXSAN convention (MSC, 1989)'
;
;
    Example 1 - data set n-alkylation_C-4 of Hussain, Fleming, Norman & Chang
                [Acta Cryst. (1996), C52, 1010-1012].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_ORIENT_MATRIX category record details
               about the orientation matrix used in the measurement of the
               diffraction intensities.
;

data_diffrn_orient_matrix_type
    _name                      '_diffrn_orient_matrix_type'
    _category                    diffrn_orient_matrix
    _type                        char
    _definition
;              A description of the orientation matrix type and how it should
               be applied to define the orientation of the crystal precisely
               with respect to the diffractometer axes.
;

data_diffrn_orient_matrix_UB_
    loop_ _name                '_diffrn_orient_matrix_UB_11'
                               '_diffrn_orient_matrix_UB_12'
                               '_diffrn_orient_matrix_UB_13'
                               '_diffrn_orient_matrix_UB_21'
                               '_diffrn_orient_matrix_UB_22'
                               '_diffrn_orient_matrix_UB_23'
                               '_diffrn_orient_matrix_UB_31'
                               '_diffrn_orient_matrix_UB_32'
                               '_diffrn_orient_matrix_UB_33'
    _category                    diffrn_orient_matrix
    _type                        numb
    _definition
;              The elements of the diffractometer orientation matrix. These
               define the dimensions of the reciprocal cell and its orientation
               to the local diffractometer axes. See _diffrn_orient_matrix_type.
;

#########################
## DIFFRN_ORIENT_REFLN ##
#########################

data_diffrn_orient_refln_[]
    _name                      '_diffrn_orient_refln_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _diffrn_orient_refln_index_h
    _diffrn_orient_refln_index_k
    _diffrn_orient_refln_index_l
    _diffrn_orient_refln_angle_theta
    _diffrn_orient_refln_angle_phi
    _diffrn_orient_refln_angle_omega
    _diffrn_orient_refln_angle_kappa
      -3   2   3    7.35   44.74   2.62    17.53
      -4   1   0    9.26   83.27   8.06     5.79
       0   0   6    5.85  -43.93 -25.36    86.20
       2   1   3    7.36  -57.87   6.26     5.42
       0   0  -6    5.85 -161.59  36.96   -86.79
      -3   1   0    6.74   80.28   5.87     2.60
       2   0   3    5.86  -76.86  -0.17    21.34
       0   0  12   11.78  -44.02 -19.51    86.41
       0   0 -12   11.78 -161.67  42.81   -86.61
      -5   1   0   11.75   86.24   9.16     7.44
       0   4   6   11.82  -19.82  10.45     4.19
       5   0   6   14.13  -77.28  10.17    15.34
       8   0   0   20.79  -77.08  25.30   -13.96
;
;
    Example 1 - typical output listing from an Enraf-Nonius CAD-4
    diffractometer.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_ORIENT_REFLN category record details
               about the reflections that define the orientation matrix used in
               the measurement of the diffraction intensities.
;

data_diffrn_orient_refln_angle_
    loop_ _name                '_diffrn_orient_refln_angle_chi'
                               '_diffrn_orient_refln_angle_kappa'
                               '_diffrn_orient_refln_angle_omega'
                               '_diffrn_orient_refln_angle_phi'
                               '_diffrn_orient_refln_angle_psi'
                               '_diffrn_orient_refln_angle_theta'
    _category                    diffrn_orient_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_orient_refln_index_'
    _units                       deg
    _units_detail              'degrees'
    _definition
;              Diffractometer angles of a reflection used to define
               the orientation matrix in degrees. See
               _diffrn_orient_matrix_UB_ and
               _diffrn_orient_refln_index_h, *_k and *_l.
;

data_diffrn_orient_refln_index_
    loop_ _name                '_diffrn_orient_refln_index_h'
                               '_diffrn_orient_refln_index_k'
                               '_diffrn_orient_refln_index_l'
    _category                    diffrn_orient_refln
    _type                        numb
    _list                        yes
    _list_mandatory              yes
    _definition
;              The indices of a reflection used to define the orientation
               matrix. See _diffrn_orient_matrix_.
;

######################
## DIFFRN_RADIATION ##
######################

data_diffrn_radiation_[]
    _name                      '_diffrn_radiation_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _diffrn_radiation_type             'Cu K\a'
    _diffrn_radiation_monochromator    'graphite'
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_RADIATION category describe the
               radiation used in measuring the diffraction intensities, its
               collimation and monochromatization before the sample.

               Post-sample treatment of the beam is described by data items
               in the DIFFRN_DETECTOR category.
;

data_diffrn_radiation_collimation
    _name                      '_diffrn_radiation_collimation'
    _category                    diffrn_radiation
    _type                        char
    loop_ _example             '0.3 mm double-pinhole'
                               '0.5 mm'
                               'focusing mirrors'
    _definition
;              The collimation or focusing applied to the radiation.
;

data_diffrn_radiation_filter_edge
    _name                      '_diffrn_radiation_filter_edge'
    _category                    diffrn_radiation
    _type                        numb
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              Absorption edge in angstroms of the radiation filter used.
;

data_diffrn_radiation_inhomogeneity
    _name                      '_diffrn_radiation_inhomogeneity'
    _category                    diffrn_radiation
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              Half-width in millimetres of the incident beam in the
               direction perpendicular to the diffraction plane.
;

data_diffrn_radiation_monochromator
    _name                      '_diffrn_radiation_monochromator'
    _category                    diffrn_radiation
    _type                        char
    loop_ _example              'Zr filter'   'Ge 220'   'none'
                                'equatorial mounted graphite'
    _definition
;              The method used to obtain monochromatic radiation. If a mono-
               chromator crystal is used, the material and the indices of the
               Bragg reflection are specified.
;

data_diffrn_radiation_polarisn_norm
    _name                      '_diffrn_radiation_polarisn_norm'
    _category                    diffrn_radiation
    _type                        numb
    _enumeration_range           -180.0:180.0
    _units                       deg
    _units_detail              'degrees'
    _definition
;              The angle in degrees, as viewed from the specimen, between the
               perpendicular component of the polarization and the diffraction
               plane. See _diffrn_radiation_polarisn_ratio.
;

data_diffrn_radiation_polarisn_ratio
    _name                      '_diffrn_radiation_polarisn_ratio'
    _category                    diffrn_radiation
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              Polarization ratio of the diffraction beam incident on the
               crystal. It is the ratio of the perpendicularly polarized to the
               parallel polarized components of the radiation. The perpendicular
               component forms an angle of _diffrn_radiation_polarisn_norm to
               the normal to the diffraction plane of the sample (i.e. the plane
               containing the incident and reflected beams).
;

data_diffrn_radiation_probe
    _name                      '_diffrn_radiation_probe'
    _category                    diffrn_radiation
    _type                        char
    loop_ _enumeration           x-ray
                                 neutron
                                 electron
                                 gamma
    _definition
;             The nature of the radiation used (i.e. the name of the
              subatomic particle or the region of the electromagnetic
              spectrum). It is strongly recommended that this information
              be given, so that the probe radiation can be simply determined.
;

data_diffrn_radiation_type
    _name                      '_diffrn_radiation_type'
    _category                    diffrn_radiation
    _type                        char
    loop_ _example               'Cu K\a'        'Cu K\a~1~'
                                 'Cu K-L~2,3~'   white-beam
    _definition
;              The type of the radiation. This is used to give a more
               detailed description than _diffrn_radiation_probe and is
               typically a description of the X-ray wavelength in Siegbahn
               notation.
;

data_diffrn_radiation_xray_symbol
    _name                      '_diffrn_radiation_xray_symbol'
    _category                    diffrn_radiation
    _type                        char
    loop_ _enumeration
          _enumeration_detail
          K-L~3~        'K\a~1~ in older Siegbahn notation'
          K-L~2~        'K\a~2~ in older Siegbahn notation'
          K-M~3~        'K\b~1~ in older Siegbahn notation'
          K-L~2,3~      'use where K-L~3~ and K-L~2~ are not resolved'
    _definition
;              The IUPAC symbol for the X-ray wavelength for the probe
               radiation.
;

###################################
### DIFFRN_RADIATION_WAVELENGTH ###
###################################

data_diffrn_radiation_wavelength_[]
    _name                      '_diffrn_radiation_wavelength_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _diffrn_radiation_wavelength       1.5418
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_RADIATION_WAVELENGTH category describe
               the wavelength of the radiation used in measuring the diffraction
               intensities. Items may be looped to identify and assign weights
               to distinct wavelength components from a polychromatic beam.
;

data_diffrn_radiation_wavelength
    _name                      '_diffrn_radiation_wavelength'
    _category                    diffrn_radiation_wavelength
    _type                        numb
    _list                        both
    _list_reference            '_diffrn_radiation_wavelength_id'
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The radiation wavelength in angstroms.
;

data_diffrn_radiation_wavelength_determination
    _name                      '_diffrn_radiation_wavelength_determination'
    _category                    diffrn_radiation_wavelength
    _type                        char
    _list                        both
    _list_reference            '_diffrn_radiation_wavelength_id'
    loop_ _enumeration
          _enumeration_detail
                                 fundamental           
;                                        Wavelength that is a
                                         fundamental property of matter
                                         e.g. MoK\alpha.
;
                                 estimated               
;                                        Estimated from secondary information
                                         e.g. monochromator angle or time
                                         of flight.
;
                                 refined                 
;                                        Based on refinement using a standard
                                         material with known cell parameters.
;
    _definition
;              The method of determination of incident wavelength. 
;

data_diffrn_radiation_wavelength_id
    _name                      '_diffrn_radiation_wavelength_id'
    _category                    diffrn_radiation_wavelength
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_child           '_diffrn_refln_wavelength_id'
    loop_ _example               x1  x2  neut
    _definition
;              An arbitrary code identifying each value of
               _diffrn_radiation_wavelength. Items in the DIFFRN_RADIATION
               category are looped when multiple wavelengths are used.
               This code is used to link with the _diffrn_refln_ list. It
               must match with one of the _diffrn_refln_wavelength_id codes.
;

data_diffrn_radiation_wavelength_wt
    _name                      '_diffrn_radiation_wavelength_wt'
    _category                    diffrn_radiation_wavelength
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_radiation_wavelength_id'
    _enumeration_range           0.0:1.0
    _enumeration_default         1.0
    _definition
;              The relative weight of a wavelength identified by the code
               _diffrn_radiation_wavelength_id in the list of wavelengths.
;

##################
## DIFFRN_REFLN ##
##################

data_diffrn_refln_[]
    _name                      '_diffrn_refln_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
        _diffrn_refln_index_h
        _diffrn_refln_index_k
        _diffrn_refln_index_l
        _diffrn_refln_angle_chi
        _diffrn_refln_scan_rate
        _diffrn_refln_counts_bg_1
        _diffrn_refln_counts_total
        _diffrn_refln_counts_bg_2
        _diffrn_refln_angle_theta
        _diffrn_refln_angle_phi
        _diffrn_refln_angle_omega
        _diffrn_refln_angle_kappa
        _diffrn_refln_scan_width
        _diffrn_refln_elapsed_time

 0  0 -16  0. 4.12  28 127  36  33.157  -75.846  16.404   50.170  1.516 19.43
 0  0 -15  0. 4.12  38 143  28  30.847  -75.846  14.094   50.170  1.516 19.82
 0  0 -14  0. 1.03 142 742 130  28.592  -75.846  11.839   50.170  1.516 21.32
 0  0 -13  0. 4.12  26 120  37  26.384  -75.846   9.631   50.170  1.450 21.68
 0  0 -12  0. 0.97 129 618 153  24.218  -75.846   7.464   50.170  1.450 23.20
 0  0 -11  0. 4.12  33 107  38  22.087  -75.846   5.334   50.170  1.384 23.55
 0  0 -10  0. 4.12  37 146  33  19.989  -75.846   3.235   50.170  1.384 23.90
 0  0  -9  0. 4.12  50 179  49  17.918  -75.846   1.164   50.170  1.384 24.25
    # - - - - data truncated for brevity - - - -
 3  4  -4  0. 1.03  69 459  73  30.726  -53.744  46.543  -47.552  1.516 2082.58
 3  4  -5  0. 1.03  91 465  75  31.407  -54.811  45.519  -42.705  1.516 2084.07
 3 14  -6  0. 1.03  84 560  79  32.228  -55.841  44.745  -38.092  1.516 2085.57
    # - - - - data truncated for brevity - - - -
;
;
    Example 1 - extracted from the CAD-4 listing for Tl~2~Cd~2~(SO~4~)~3~ at
                85 K (unpublished).
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_REFLN category record details about
               the intensities measured in the diffraction experiment.

               The DIFFRN_REFLN data items refer to individual intensity
               measurements and must be included in looped lists.

               (The DIFFRN_REFLNS data items specify the parameters that apply
               to all intensity  measurements. The DIFFRN_REFLNS data items
               are not looped.)
;

data_diffrn_refln_angle_
    loop_ _name                '_diffrn_refln_angle_chi'
                               '_diffrn_refln_angle_kappa'
                               '_diffrn_refln_angle_omega'
                               '_diffrn_refln_angle_phi'
                               '_diffrn_refln_angle_psi'
                               '_diffrn_refln_angle_theta'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _units                       deg
    _units_detail              'degrees'
    _definition
;              The diffractometer angles of a reflection in degrees. These
               correspond to the specified orientation matrix and the original
               measured cell before any subsequent cell transformations.
;

data_diffrn_refln_attenuator_code
    _name                      '_diffrn_refln_attenuator_code'
    _category                    diffrn_refln
    _type                        char
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _list_link_parent          '_diffrn_attenuator_code'
    _definition
;              The code identifying the attenuator setting for this reflection.
               This code must match one of the _diffrn_attenuator_code values.
;

data_diffrn_refln_class_code
    _name                      '_diffrn_refln_class_code'
    _category                    diffrn_refln
    _type                        char
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _list_link_parent          '_diffrn_reflns_class_code'
    _definition
;              The code identifying the class to which this reflection has
               been assigned. This code must match a value of
               _diffrn_reflns_class_code. Reflections may be grouped into
               classes for a variety of purposes. For example, for modulated
               structures each reflection class may be defined by the
               number m=sum|m~i~|, where the m~i~ are the integer coefficients
               that, in addition to h,k,l, index the corresponding diffraction
               vector in the basis defined for the reciprocal lattice.
;

data_diffrn_refln_counts_
    loop_ _name                '_diffrn_refln_counts_bg_1'
                               '_diffrn_refln_counts_bg_2'
                               '_diffrn_refln_counts_net'
                               '_diffrn_refln_counts_peak'
                               '_diffrn_refln_counts_total'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _definition
;              The diffractometer counts for the measurements: background
               before the peak, background after the peak, net counts after
               background removed, counts for peak scan or position, and the
               total counts (background plus peak).
;

data_diffrn_refln_crystal_id
    _name                      '_diffrn_refln_crystal_id'
    _category                    diffrn_refln
    _type                        char
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _list_link_parent          '_exptl_crystal_id'
    _definition
;              Code identifying each crystal if multiple crystals are used. Is
               used to link with _exptl_crystal_id in the _exptl_crystal_ list.
;

data_diffrn_refln_detect_slit_
    loop_ _name                '_diffrn_refln_detect_slit_horiz'
                               '_diffrn_refln_detect_slit_vert'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _enumeration_range           0.0:90.0
    _units                       deg
    _units_detail              'degrees'
    _definition
;              Total slit apertures in degrees in the diffraction plane
               (*_horiz) and perpendicular to the diffraction plane (*_vert).
;

data_diffrn_refln_elapsed_time
    _name                      '_diffrn_refln_elapsed_time'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _enumeration_range           0.0:
    _units                       min
    _units_detail              'minutes'
    _definition
;              Elapsed time in minutes from the start of the diffraction
               experiment to the measurement of this intensity.
;

data_diffrn_refln_index_
    loop_ _name                '_diffrn_refln_index_h'
                               '_diffrn_refln_index_k'
                               '_diffrn_refln_index_l'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_mandatory              yes
    _definition
;              Miller indices of a measured reflection. These need not match
               the _refln_index_h, *_k, *_l values if a transformation of the
               original measured cell has taken place. Details of the cell
               transformation are given in _diffrn_reflns_reduction_process.
               See also _diffrn_reflns_transf_matrix_.
;

data_diffrn_refln_intensity_net
    _name                      '_diffrn_refln_intensity_net'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _enumeration_range           0:
    _definition
;              Net intensity calculated from the diffraction counts after
               the attenuator and standard scales have been applied.
;

data_diffrn_refln_intensity_sigma
    _name                      '_diffrn_refln_intensity_sigma'
    _category                    diffrn_refln
    _type                        numb
    _related_item              '_diffrn_refln_intensity_u'
    _related_function            replace
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _enumeration_range           0:
    _definition
;              Standard uncertainty (e.s.d.) of the net intensity calculated
               from the diffraction counts after the attenuator and standard
               scales have been applied.
;

data_diffrn_refln_intensity_u
    _name                      '_diffrn_refln_intensity_u'
    _category                    diffrn_refln
    _type                        numb
    _related_item              '_diffrn_refln_intensity_sigma'
    _related_function            alternate
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _enumeration_range           0:
    _definition
;              Standard uncertainty of the net intensity calculated from
               the diffraction counts after the attenuator and standard
               scales have been applied.
;

data_diffrn_refln_scale_group_code
    _name                      '_diffrn_refln_scale_group_code'
    _category                    diffrn_refln
    _type                        char
    _list                        yes
    _list_link_parent          '_diffrn_scale_group_code'
    _list_reference            '_diffrn_refln_index_'
    _definition
;              The code identifying the scale applicable to this reflection.
               This code must match with a specified _diffrn_scale_group_code
               value.
;

data_diffrn_refln_scan_mode
    _name                      '_diffrn_refln_scan_mode'
    _category                    diffrn_refln
    _type                        char
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    loop_ _enumeration
          _enumeration_detail    om  'omega scan'
                                 ot  'omega/2theta scan'
                                 q   'Q scans (arbitrary reciprocal directions)'
    _definition
;              The code identifying the mode of scanning for measurements
               using a diffractometer. See _diffrn_refln_scan_width and
               _diffrn_refln_scan_mode_backgd.
;

data_diffrn_refln_scan_mode_backgd
    _name                      '_diffrn_refln_scan_mode_backgd'
    _category                    diffrn_refln
    _type                        char
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    loop_ _enumeration
          _enumeration_detail    st  'stationary counter background'
                                 mo  'moving counter background'
    _definition
;              The code identifying the mode of scanning a reflection to measure
               the background intensity.
;

data_diffrn_refln_scan_rate
    _name                      '_diffrn_refln_scan_rate'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _enumeration_range           0.0:
    _units                      deg/min
    _units_detail              'degrees per minute'
    _definition
;              The rate of scanning a reflection in
               degrees per minute to measure the intensity.
;

data_diffrn_refln_scan_time_backgd
    _name                      '_diffrn_refln_scan_time_backgd'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _enumeration_range           0.0:
    _units                      sec
    _units_detail              'seconds'
    _definition
;              The time spent measuring each background in seconds.
;

data_diffrn_refln_scan_width
    _name                      '_diffrn_refln_scan_width'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _enumeration_range           0.0:90.0
    _units                       deg
    _units_detail              'degrees'
    _definition
;              The scan width in degrees of the scan mode defined by the code
               _diffrn_refln_scan_mode.
;

data_diffrn_refln_sint/lambda
    _name                      '_diffrn_refln_sint/lambda'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _enumeration_range           0.0:
    _units                       A^-1^
    _units_detail              'reciprocal angstroms'
    _definition
;              The (sin theta)/lambda value in reciprocal angstroms for
               this reflection.
;

data_diffrn_refln_standard_code
    _name                      '_diffrn_refln_standard_code'
    _category                    diffrn_refln
    _type                        char
    _list                        yes
    _list_link_parent          '_diffrn_standard_refln_code'
    _list_reference            '_diffrn_refln_index_'
    loop_ _example              1 2 3 s1 s2 s3 A B C
    _definition
;              A code indicating that this reflection was measured as a
               standard reflection. The value must be '.' or match one of
               the _diffrn_standard_refln_code values.
;

data_diffrn_refln_wavelength
    _name                      '_diffrn_refln_wavelength'
    _category                    diffrn_refln
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_refln_index_'
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The mean wavelength in angstroms of the radiation used to measure
               the intensity of this reflection. This is an important parameter
               for reflections measured using energy-dispersive detectors or the
               Laue method.
;


data_diffrn_refln_wavelength_id
    _name                      '_diffrn_refln_wavelength_id'
    _category                    diffrn_refln
    _type                        char
    _list                        yes
    _list_link_parent          '_diffrn_radiation_wavelength_id'
    _list_reference            '_diffrn_refln_index_'
    loop_ _example               x1  x2  neut
    _definition
;              Code identifying the wavelength in the _diffrn_radiation_ list.
;

###################
## DIFFRN_REFLNS ##
###################

data_diffrn_reflns_[]
    _name                      '_diffrn_reflns_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _diffrn_reflns_number              1592
    _diffrn_reflns_av_R_equivalents    0
    _diffrn_reflns_av_unetI/netI       .027
    _diffrn_reflns_limit_h_min         0
    _diffrn_reflns_limit_h_max         6
    _diffrn_reflns_limit_k_min        -17
    _diffrn_reflns_limit_k_max         0
    _diffrn_reflns_limit_l_min         0
    _diffrn_reflns_limit_l_max         22
    _diffrn_reflns_theta_min           3.71
    _diffrn_reflns_theta_max           61.97
;
;
        Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_REFLNS category record details about
               the set of intensities measured in the diffraction experiment.

               The DIFFRN_REFLNS data items specify the parameters that apply
               to all intensity measurements. The DIFFRN_REFLNS data items
               are not looped.

               (The DIFFRN_REFLN data items refer to individual intensity
               measurements and must be included in looped lists.)
;

data_diffrn_reflns_av_R_equivalents
    _name                      '_diffrn_reflns_av_R_equivalents'
    _category                    diffrn_reflns
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              The residual [sum av|del(I)| / sum |av(I)|] for
               symmetry-equivalent reflections used to calculate the
               average intensity av(I). The av|del(I)| term is the
               average absolute difference between av(I) and the
               individual symmetry-equivalent intensities.
;

data_diffrn_reflns_av_sigmaI/netI
    _name                      '_diffrn_reflns_av_sigmaI/netI'
    _category                    diffrn_reflns
    _type                        numb
    _related_item              '_diffrn_reflns_av_unetI/netI'
    _related_function            replace
    _enumeration_range           0.0:
    _definition
;              Measure [sum |u(net I)|/sum|net I|] for all measured reflections.
;

data_diffrn_reflns_av_unetI/netI
    _name                      '_diffrn_reflns_av_unetI/netI'
    _category                    diffrn_reflns
    _type                        numb
    _related_item              '_diffrn_reflns_av_sigmaI/netI'
    _related_function            alternate
    _enumeration_range           0.0:
    _definition
;              Measure [sum |u(net I)|/sum|net I|] for all measured reflections.
;

data_diffrn_reflns_Laue_measured_fraction_full
    _name                      '_diffrn_reflns_Laue_measured_fraction_full'
    _category                    diffrn_reflns         
    _type                        numb
    _related_item              '_diffrn_measured_fraction_theta_full'    
    _related_function            alternate
    _enumeration_range           0.95:1.0
    _definition
;              Fraction of Laue unique reflections (symmetry-independent in
               the Laue group) measured out to the resolution given in
               _diffrn_reflns_resolution_full or _diffrn_reflns_theta_full.
               The Laue group always contains a centre of symmetry so that
               the reflection h,k,l is always equivalent to the reflection
               -h,-k,-l even in space groups without a centre of symmetry.
               This number should not be less than 0.95, since it represents
               the fraction of reflections measured in the part of the
               diffraction pattern that is essentially complete.
;

data_diffrn_reflns_Laue_measured_fraction_max
    _name                      '_diffrn_reflns_Laue_measured_fraction_max'
    _category                    diffrn_reflns   
    _type                        numb
    _related_item              '_diffrn_measured_fraction_theta_max'
    _related_function            alternate
    _enumeration_range           0:1.0
    _definition
;              Fraction of Laue unique reflections (symmetry-independent in
               the Laue group) measured out to the resolution given in
               _diffrn_reflns_resolution_max or _diffrn_reflns_theta_max.
               The Laue group always contains a centre of symmetry so that the
               reflection h,k,l is always equivalent to the reflection -h,-k,-l
               even in space groups without a centre of symmetry.
;

data_diffrn_reflns_limit_
    loop_ _name                '_diffrn_reflns_limit_h_max'
                               '_diffrn_reflns_limit_h_min'
                               '_diffrn_reflns_limit_k_max'
                               '_diffrn_reflns_limit_k_min'
                               '_diffrn_reflns_limit_l_max'
                               '_diffrn_reflns_limit_l_min'
    _category                    diffrn_reflns
    _type                        numb
    _definition
;              The limits on the Miller indices of the intensities specified
               by _diffrn_refln_index_h, *_k, *_l.
;

data_diffrn_reflns_number
    _name                      '_diffrn_reflns_number'
    _category                    diffrn_reflns
    _type                        numb
    _enumeration_range           0:
    _definition
;              The total number of measured intensities, excluding
               reflections that are classed as systematically absent arising
               from translational symmetry in the crystal unit cell.
;

data_diffrn_reflns_point_group_measured_fraction_full
    _name                    '_diffrn_reflns_point_group_measured_fraction_full'
    _category                    diffrn_reflns         
    _type                        numb
    _related_item              '_diffrn_measured_fraction_theta_full'    
    _related_function            alternate
    _enumeration_range           0.95:1.0
    _definition
;              Fraction of crystal point-group unique reflections (i.e.
               symmetry-independent in the crystal point group) measured
               out to the resolution given in _diffrn_reflns_resolution_full
               or _diffrn_reflns_theta_full. For space groups that do not
               contain a centre of symmetry the reflections h,k,l and
               -h,-k,-l are independent. This number should not be less
               than 0.95, since it represents the fraction of reflections
               measured in the part of the diffraction pattern that is
               essentially complete.
;

data_diffrn_reflns_point_group_measured_fraction_max
    _name                    '_diffrn_reflns_point_group_measured_fraction_max'
    _category                    diffrn_reflns   
    _type                        numb
    _related_item              '_diffrn_measured_fraction_theta_max'
    _related_function            alternate
    _enumeration_range           0:1.0
    _definition
;              Fraction of crystal point-group unique reflections (i.e.
               symmetry-independent in the crystal point group) measured
               out to the resolution given in _diffrn_reflns_resolution_max
               or _diffrn_reflns_theta_max. For space groups that do not
               contain a centre of symmetry the reflections h,k,l and
               -h,-k,-l are independent.
;

data_diffrn_reflns_reduction_process
    _name                      '_diffrn_reflns_reduction_process'
    _category                    diffrn_reflns
    _type                        char
    _example                    'data averaged using Fisher test'
    _definition
;              A description of the process used to reduce the intensities
               into structure-factor magnitudes.
;

data_diffrn_reflns_resolution_full
    _name                      '_diffrn_reflns_resolution_full'
    _category                    diffrn_reflns
    _type                        numb
    _enumeration_range           0.0:
    _units                       A^-1^
    _units_detail              'reciprocal angstroms'
    _related_item              '_diffrn_reflns_theta_full'
    _related_function            alternate
    _definition
;              The resolution in reciprocal angstroms at which the measured
               reflection count is close to complete. The fraction of unique
               reflections measured out to this angle is given by
               _diffrn_measured_fraction_theta_full.
;

data_diffrn_reflns_resolution_max
    _name                      '_diffrn_reflns_resolution_max'
    _category                    diffrn_reflns
    _type                        numb
    _enumeration_range           0.0:
    _units                       A^-1^
    _units_detail              'reciprocal angstroms'
    _related_item              '_diffrn_reflns_theta_max'
    _related_function            alternate
    _definition
;              Maximum resolution in reciprocal angstroms of the measured
               diffraction pattern. The fraction of unique reflections
               measured out to this angle is given by
               _diffrn_measured_fraction_theta_max
;

data_diffrn_reflns_theta_full
    _name                      '_diffrn_reflns_theta_full'
    _category                    diffrn_reflns
    _type                        numb
    _enumeration_range           0.0:90.0
    _units                       deg
    _units_detail              'degrees'
    _definition
;              The theta angle (in degrees) at which the measured reflection
               count is close to complete. The fraction of unique reflections
               measured out to this angle is given by
               _diffrn_measured_fraction_theta_full.
;

data_diffrn_reflns_theta_max
    _name                      '_diffrn_reflns_theta_max'
    _category                    diffrn_reflns
    _type                        numb
    _enumeration_range           0.0:90.0
    _units                       deg
    _units_detail              'degrees'
    _definition
;              Maximum theta angle in degrees for the measured intensities.
               The fraction of unique reflections measured out to this angle
               is given by _diffrn_measured_fraction_theta_max
;

data_diffrn_reflns_theta_min
    _name                      '_diffrn_reflns_theta_min'
    _category                    diffrn_reflns
    _type                        numb
    _enumeration_range           0.0:90.0
    _units                       deg
    _units_detail              'degrees'
    _definition
;              Minimum theta angle in degrees for the measured intensities.
;

data_diffrn_reflns_transf_matrix_
    loop_ _name                '_diffrn_reflns_transf_matrix_11'
                               '_diffrn_reflns_transf_matrix_12'
                               '_diffrn_reflns_transf_matrix_13'
                               '_diffrn_reflns_transf_matrix_21'
                               '_diffrn_reflns_transf_matrix_22'
                               '_diffrn_reflns_transf_matrix_23'
                               '_diffrn_reflns_transf_matrix_31'
                               '_diffrn_reflns_transf_matrix_32'
                               '_diffrn_reflns_transf_matrix_33'
    _category                    diffrn_reflns
    _type                        numb
    _definition
;              Elements of the matrix used to transform the diffraction
               reflection indices _diffrn_refln_index_h, *_k, *_l into the
               _refln_index_h, *_k, *_l indices.
                                          |11 12 13|
                     (h k l) diffraction  |21 22 23|  =  (h' k' l')
                                          |31 32 33|
;
#########################
## DIFFRN_REFLNS_CLASS ##
#########################

data_diffrn_reflns_class_[]
    _name                      '_diffrn_reflns_class_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
        _diffrn_reflns_class_number
        _diffrn_reflns_class_d_res_high
        _diffrn_reflns_class_d_res_low
        _diffrn_reflns_class_av_R_eq
        _diffrn_reflns_class_code
        _diffrn_reflns_class_description
            1580 0.551 6.136 0.015 'Main'
                                    'm=0; main reflections'
            1045 0.551 6.136 0.010
                       'Sat1' 'm=1; first-order satellites'
;
;
    Example 1 - example corresponding to the one-dimensional incommensurately
                modulated structure of K~2~SeO~4~. Each reflection class is
                defined by the number m=sum|m~i~|, where the m~i~ are the
                integer coefficients that, in addition to h,k,l, index the
                corresponding diffraction vector in the basis defined for
                the reciprocal lattice.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      _definition
;              Data items in the DIFFRN_REFLNS_CLASS category record details
               about the classes of reflections measured in the diffraction
               experiment.
;

data_diffrn_reflns_class_av_R_eq
    _name                      '_diffrn_reflns_class_av_R_eq'
    _category                    diffrn_reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual
               [sum av|del(I)|/sum|av(I)|] for symmetry-equivalent reflections
               used to calculate the average intensity av(I). The av|del(I)|
               term is the average absolute difference between av(I) and the
               individual intensities.
;

data_diffrn_reflns_class_av_sgI/I
    _name                      '_diffrn_reflns_class_av_sgI/I'
    _category                    diffrn_reflns_class
    _type                        numb
    _related_item              '_diffrn_reflns_class_av_uI/I'
    _related_function            replace
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              Measure [sum|u(net I)|/sum|net I|] for all measured intensities
               in a reflection class.
;

data_diffrn_reflns_class_av_uI/I
    _name                      '_diffrn_reflns_class_av_uI/I'
    _category                    diffrn_reflns_class
    _type                        numb
    _related_item              '_diffrn_reflns_class_av_sgI/I'
    _related_function            alternate
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              Measure [sum|u(net I)|/sum|net I|] for all measured intensities
               in a reflection class.
;

data_diffrn_reflns_class_code
    _name                      '_diffrn_reflns_class_code'
    _category                    diffrn_reflns_class
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_child           '_diffrn_refln_class_code'
    loop_ _example               '1'
                                 'm1'
                                 's2'
    _definition
;              The code identifying a certain reflection class.
;

data_diffrn_reflns_class_d_res_high
    _name                      '_diffrn_reflns_class_d_res_high'
    _category                    diffrn_reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              The smallest value in angstroms of the interplanar
               spacings of the reflections in each reflection class.
               This is called the highest resolution for this reflection class.
;

data_diffrn_reflns_class_d_res_low
    _name                      '_diffrn_reflns_class_d_res_low'
    _category                    diffrn_reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              The highest value in angstroms of the interplanar
               spacings of the reflections in each reflection class.
               This is called the lowest resolution for this reflection class.
;

data_diffrn_reflns_class_description
    _name                      '_diffrn_reflns_class_description'
    _category                    diffrn_reflns_class
    _type                        char
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    loop_ _example               'm=1 first order satellites'
                                 'H0L0 common projection reflections'
    _definition
;              Description of each reflection class.
;

data_diffrn_reflns_class_number
    _name                      '_diffrn_reflns_class_number'
    _category                    diffrn_reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_reflns_class_code'
    _enumeration_range           0:
    _definition
;              The total number of measured intensities for each reflection
               class, excluding the systematic absences arising from
               centring translations.
;

########################
## DIFFRN_SCALE_GROUP ##
########################

data_diffrn_scale_group_[]
    _name                      '_diffrn_scale_group_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _diffrn_scale_group_code
    _diffrn_scale_group_I_net
      1    .86473
      2   1.0654
;
;
    Example 1 - hypothetical example.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_SCALE_GROUP category record details
               of the scaling factors applied to place all intensities in
               the reflection lists on a common scale.

               Scaling groups might, for instance, correspond to each film
               in a multi-film data set or each crystal in a multi-crystal
               data set.
;

data_diffrn_scale_group_code
    _name                      '_diffrn_scale_group_code'
    _category                    diffrn_scale_group
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_child           '_diffrn_refln_scale_group_code'
    loop_ _example               1 2 3 s1 A B c1 c2 c3
    _definition
;              The code identifying a specific measurement group (e.g. for
               multi-film or multi-crystal data). The code must match a
               _diffrn_refln_scale_group_code in the reflection list.
;

data_diffrn_scale_group_I_net
    _name                      '_diffrn_scale_group_I_net'
    _category                    diffrn_scale_group
    _type                        numb
    _list                        yes
    _list_reference            '_diffrn_scale_group_code'
    _enumeration_range           0.0:
    _definition
;              The scale for a specific measurement group which is to be
               multiplied with the net intensity to place all intensities
               in the _diffrn_refln_ or _refln_ list on a common scale.
;

###################
## DIFFRN_SOURCE ##
###################

data_diffrn_source_[]
    _name                      '_diffrn_source_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _diffrn_source               'rotating anode X-ray tube'
    _diffrn_source_type          'Rigaku RU-200'
    _diffrn_source_power         50
    _diffrn_source_current       180
    _diffrn_source_size          '8 mm x 0.4 mm broad focus'
;
;
    Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_SOURCE category record details of
               the source of radiation used in the diffraction experiment.
;

data_diffrn_radiation_source
    _name                      '_diffrn_radiation_source'
    _category                    diffrn_source
    _type                        char
    _related_item              '_diffrn_source'
    _related_function            replace
    _definition
;              The source of radiation.
;

data_diffrn_source
    _name                      '_diffrn_source'
    _category                    diffrn_source
    _type                        char
    _related_item              '_diffrn_radiation_source'
    _related_function            alternate
    loop_
    _example                   'sealed X-ray tube'
                               'nuclear reactor'
                               'spallation source'
                               'electron microscope'
                               'rotating-anode X-ray tube'
                               'synchrotron'
    _definition
;              The general class of the source of radiation.
;

data_diffrn_source_current
    _name                      '_diffrn_source_current'
    _category                    diffrn_source
    _type                        numb
    _enumeration_range           0.0:
    _units                       mA
    _units_detail              'milliamperes'
    _definition
;              The current in milliamperes at which the radiation source was
               operated.
;

data_diffrn_source_details
    _name                      '_diffrn_source_details'
    _category                    diffrn_source
    _type                        char
    _definition
;              A description of special aspects of the source.
;

data_diffrn_source_power
    _name                      '_diffrn_source_power'
    _category                    diffrn_source
    _type                        numb
    _enumeration_range           0.0:
    _units                       kW
    _units_detail              'kilowatts'
    _definition
;              The power in kilowatts at which the radiation source was
               operated.
;

data_diffrn_source_size
    _name                      '_diffrn_source_size'
    _category                    diffrn_source
    _type                        char
    loop_
    _example                   '8mm x 0.4 mm fine-focus'
                               'broad focus'
    _definition
;              The dimensions of the source as viewed from the sample.
;

data_diffrn_source_take-off_angle
    _name                      '_diffrn_source_take-off_angle'
    _category                    diffrn_source
    _type                        numb
    _enumeration_range           0:90
    _units                       degrees
    _example                     1.53
    _definition
;              The complement of the angle in degrees between the normal
               to the surface of the X-ray tube target and the primary
               X-ray beam for beams generated by traditional X-ray tubes.
;

data_diffrn_source_target
    _name                      '_diffrn_source_target'
    _category                    diffrn_source
    _type                        char
    loop_ _enumeration
        H  He  Li  Be  B  C  N  O  F  Ne  Na  Mg  Al  Si  P  S  Cl
        Ar  K  Ca  Sc  Ti  V  Cr  Mn  Fe  Co  Ni  Cu  Zn  Ga  Ge
        As  Se  Br  Kr  Rb  Sr  Y  Zr  Nb  Mo  Tc  Ru  Rh  Pd  Ag
        Cd  In  Sn  Sb  Te  I  Xe  Cs  Ba  La  Ce  Pr  Nd  Pm  Sm
        Eu  Gd  Tb  Dy  Ho  Er  Tm  Yb  Lu  Hf  Ta  W  Re  Os  Ir
        Pt  Au  Hg  Tl  Pb  Bi  Po  At  Rn  Fr  Ra  Ac  Th  Pa  U
        Np  Pu  Am  Cm  Bk  Cf  Es  Fm  Md  No  Lr
    _definition
;              The chemical element symbol for the X-ray target
               (usually the anode) used to generate X-rays.
               This can also be used for spallation sources.
;

data_diffrn_source_type
    _name                      '_diffrn_source_type'
    _category                    diffrn_source
    _type                        char
    loop_
    _example                   'NSLS beamline X8C'
                               'Rigaku RU200'
    _definition
;              The make, model or name of the source of radiation.
;

data_diffrn_source_voltage
    _name                      '_diffrn_source_voltage'
    _category                    diffrn_source
    _type                        numb
    _enumeration_range           0.0:
    _units                       kV
    _units_detail              'kilovolts'
    _definition
;              The voltage in kilovolts at which the radiation source was
               operated.
;

###########################
## DIFFRN_STANDARD_REFLN ##
###########################

data_diffrn_standard_refln_[]
    _name                      '_diffrn_standard_refln_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _diffrn_standard_refln_index_h
    _diffrn_standard_refln_index_k
    _diffrn_standard_refln_index_l
    3 2 4    1 9 1    3 0 10
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_STANDARD_REFLN category record details
               about the reflections treated as standards during the measurement
               of the diffraction intensities.

               Note that these are the individual standard reflections, not the
               results of the analysis of the standard reflections.
;

data_diffrn_standard_refln_code
    _name                      '_diffrn_standard_refln_code'
    _category                    diffrn_standard_refln
    _type                        char
    _list                        yes
    _list_link_child           '_diffrn_refln_standard_code'
    _list_reference            '_diffrn_standard_refln_index_'
    loop_ _example               1 2 3 s1 A B
    _definition
;              The code identifying a reflection measured as a standard
               reflection with the indices _diffrn_standard_refln_index_.
               This is the same code as the  _diffrn_refln_standard_code in
               the _diffrn_refln_ list.
;

data_diffrn_standard_refln_index_
    loop_ _name                '_diffrn_standard_refln_index_h'
                               '_diffrn_standard_refln_index_k'
                               '_diffrn_standard_refln_index_l'
    _category                    diffrn_standard_refln
    _type                        numb
    _list                        yes
    _list_mandatory              yes
    _definition
;              Miller indices of standard reflections used in the diffraction
               measurement process.
;

######################
## DIFFRN_STANDARDS ##
######################

data_diffrn_standards_[]
    _name                      '_diffrn_standards_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _diffrn_standards_number            3
    _diffrn_standards_interval_time     120
    _diffrn_standards_decay_%           0
;
;
     Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the DIFFRN_STANDARDS category record details
               about the set of standard reflections used to monitor intensity
               stability during the measurement of diffraction intensities.

               Note that these records describe properties common to the set of
               standard reflections, not the standard reflections themselves.
;

data_diffrn_standards_decay_%
    _name                      '_diffrn_standards_decay_%'
    _category                    diffrn_standards
    _type                        numb
    _type_conditions             esd
    _enumeration_range           :100
    loop_ _example 
          _example_detail
                                 0.5(1)
                               'represents a decay between 0.2% and 0.8%'
                                 -1(1)     
;                              the change in the standards lies between
                               a decay of 2% and an increase of 4%
;
                                  0.0(2)  
;                              the change in the standards lies between a
                               decay of 0.6% and an increase of 0.6%.
;
    _definition
;              The percentage decrease in the mean
               intensity of the set of standard reflections measured at the
               start of the measurement process and at the finish.  This value
               usually affords a measure of the overall decay in crystal
               quality during the diffraction measurement process.  Negative
               values are used in exceptional instances where the final
               intensities are greater than the initial ones.  If no
               measurable decay has occurred, the standard uncertainty should
               be quoted to indicate the maximum possible value the decay
               might have.  A range of 3 standard uncertainties is considered
               possible.  Thus 0.0(1) would indicate a decay of less than
               0.3% or an enhancement of less than 0.3%.
;

data_diffrn_standards_interval_
    loop_ _name                '_diffrn_standards_interval_count'
                               '_diffrn_standards_interval_time'
    _category                    diffrn_standards
    _type                        numb
    _enumeration_range           0:
    _definition
;              The number of reflection intensities, or the time in minutes,
               between the measurement of standard reflection intensities.
;

data_diffrn_standards_number
    _name                      '_diffrn_standards_number'
    _category                    diffrn_standards
    _type                        numb
    _enumeration_range           0:
    _definition
;              The number of unique standard reflections used during the
               measurement of the diffraction intensities.
;

data_diffrn_standards_scale_sigma
    _name                      '_diffrn_standards_scale_sigma'
    _category                    diffrn_standards
    _type                        numb
    _related_item              '_diffrn_standards_scale_u'
    _related_function            replace
    _enumeration_range           0.0:
    _definition
;              The standard uncertainty (e.s.d.) of the individual mean
               standard scales applied to the intensity data.
;

data_diffrn_standards_scale_u
    _name                      '_diffrn_standards_scale_u'
    _category                    diffrn_standards
    _type                        numb
    _related_item              '_diffrn_standards_scale_sigma'
    _related_function            alternate
    _enumeration_range           0.0:
    _definition
;              The standard uncertainty of the individual mean
               standard scales applied to the intensity data.
;

###########
## EXPTL ##
###########

data_exptl_[]
    _name                      '_exptl_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _exptl_absorpt_coefficient_mu     0.962
    _exptl_absorpt_correction_type    psi-scan
    _exptl_absorpt_process_details
                               'North, Phillips & Mathews (1968)'
    _exptl_absorpt_correction_T_min   0.929
    _exptl_absorpt_correction_T_max   0.997
;
;
    Example 1 - based on a paper by Steiner [Acta Cryst. (1996), C52,
                2554-2556].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the EXPTL category record details about the
               experimental work prior to the intensity measurements and
               details about the absorption-correction technique employed.
;

data_exptl_absorpt_coefficient_mu
    _name                      '_exptl_absorpt_coefficient_mu'
    _category                    exptl
    _type                        numb
    _enumeration_range           0.0:
    _units                       mm^-1^
    _units_detail              'reciprocal millimetres'
    _definition
;              The absorption coefficient mu in reciprocal millimetres
               calculated from the atomic content of the cell, the density and
               the radiation wavelength.
;

data_exptl_absorpt_correction_T_
    loop_ _name                '_exptl_absorpt_correction_T_max'
                               '_exptl_absorpt_correction_T_min'
    _category                    exptl
    _type                        numb
    _enumeration_range           0.0:1.0
    _definition
;              The maximum and minimum transmission factors applied to the
               diffraction pattern measured in this experiment. These
               factors are also referred to as the absorption correction
               A or 1/A*. As this value is the one that is applied to
               the measured intensities, it includes the correction for
               absorption by the specimen mount and diffractometer as well
               as by the specimen itself.
;

data_exptl_absorpt_correction_type
    _name                      '_exptl_absorpt_correction_type'
    _category                    exptl
    _type                        char
    loop_ _enumeration
          _enumeration_detail    analytical  'analytical from crystal shape'
                                 cylinder    'cylindrical'
                                 empirical   'empirical from intensities'
                                 gaussian    'Gaussian from crystal shape'
                                 integration 'integration from crystal shape'
                                 multi-scan  'symmetry-related measurements'
                                 none        'no absorption correction applied'
                                 numerical   'numerical from crystal shape'
                                 psi-scan    'psi-scan corrections'
                                 refdelf     'refined from delta-F'
                                 sphere      'spherical'
    _definition
;              The absorption-correction type and method. The value 'empirical'
               should NOT be used unless more detailed information is not
               available.
;

data_exptl_absorpt_process_details
    _name                      '_exptl_absorpt_process_details'
    _category                    exptl
    _type                        char
    loop_ _example               'Tompa analytical'
                                 'MolEN (Fair, 1990)'
                                 '(North, Phillips & Mathews, 1968)'
    _definition
;              Description of the absorption process applied to the
               intensities. A literature reference should be supplied
               for psi-scan techniques.
;

data_exptl_crystals_number
    _name                      '_exptl_crystals_number'
    _category                    exptl
    _type                        numb
    _enumeration_range           1:
    _definition
;              The total number of crystals used for the measurement of
               intensities.
;

data_exptl_special_details
    _name                      '_exptl_special_details'
    _category                    exptl
    _type                        char
    _definition
;              Any special information about the experimental work prior to the
               intensity measurements. See also _exptl_crystal_preparation.
;

data_exptl_transmission_factor_max
    _name                      '_exptl_transmission_factor_max'
    _category                    exptl        
    _type                        numb        
    _type_conditions             su        
    _enumeration_range           0.0:1.0
    _definition
;              The calculated maximum value of the transmission factor for
               the specimen. Its value does not include the effects of
               absorption in the specimen mount. The presence of this
               item does not imply that the structure factors have been
               corrected for absorption. The applied correction should be 
               given by _exptl_absorpt_correction_T_max.
;

data_exptl_transmission_factor_min
    _name                     '_exptl_transmission_factor_min'
    _category                    exptl        
    _type                        numb        
    _type_conditions             su        
    _enumeration_range           0.0:1.0
    _definition
;              The calculated minimum value of the transmission factor for
               the specimen. Its value does not include the effects of
               absorption in the specimen mount. The presence of this
               item does not imply that the structure factors have been
               corrected for absorption. The applied correction should be 
               given by _exptl_absorpt_correction_T_min.
;

###################
## EXPTL_CRYSTAL ##
###################

data_exptl_crystal_[]
    _name                      '_exptl_crystal_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _exptl_crystal_description          prism
    _exptl_crystal_colour               colourless
    _exptl_crystal_size_max             0.32
    _exptl_crystal_size_mid             0.27
    _exptl_crystal_size_min             0.10
    _exptl_crystal_density_diffrn       1.146
    _exptl_crystal_density_meas         ?
    _exptl_crystal_density_method       'not measured'
    _exptl_crystal_F_000                656
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;   _exptl_crystal_density_meas_gt       2.5
    _exptl_crystal_density_meas_lt       5.0
;
;
    Example 2 - using separate items to define upper and lower
                limits for a value.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;   _exptl_crystal_density_meas_temp_lt 300
;
;
    Example 3 - here the density was measured at some
                    unspecified temperature below room temperature.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the EXPTL_CRYSTAL category record details about
               experimental measurements on the crystal or crystals used,
               such as shape, size or density.
;

data_exptl_crystal_colour
    _name                      '_exptl_crystal_colour'
    _category                    exptl_crystal
    _type                        char
    _list                        both
    _list_reference            '_exptl_crystal_id'
    loop_
      _related_item
      _related_function        '_exptl_crystal_colour_lustre'      alternate
                               '_exptl_crystal_colour_modifier'    alternate
                               '_exptl_crystal_colour_primary'     alternate
    _example                   'dark green'
    _definition
;              The colour of the crystal.
;

data_exptl_crystal_colour_lustre
    _name                      '_exptl_crystal_colour_lustre'
    _category                    exptl_crystal
    _type                        char
    _list                        both
    _list_reference            '_exptl_crystal_id'
    loop_ _enumeration           metallic
                                 dull
                                 clear
    _related_item              '_exptl_crystal_colour'
    _related_function            alternate
    _definition
;             The enumeration list of standardized names developed for the
              International Centre for Diffraction Data.
              The colour of a crystal is given by the combination of
              _exptl_crystal_colour_modifier with
              _exptl_crystal_colour_primary, as in 'dark-green' or
              'bluish-violet', if necessary combined with
              _exptl_crystal_colour_lustre, as in 'metallic-green'.
;

data_exptl_crystal_colour_modifier
    _name                      '_exptl_crystal_colour_modifier'
    _category                    exptl_crystal
    _type                        char
    _list                        both
    _list_reference            '_exptl_crystal_id'
    loop_ _enumeration           light
                                 dark
                                 whitish
                                 blackish
                                 grayish
                                 brownish
                                 reddish
                                 pinkish
                                 orangish
                                 yellowish
                                 greenish
                                 bluish
    _related_item              '_exptl_crystal_colour'
    _related_function            alternate
    _definition
;             The enumeration list of standardized names developed for the
              International Centre for Diffraction Data.
              The colour of a crystal is given by the combination of
              _exptl_crystal_colour_modifier with
              _exptl_crystal_colour_primary, as in 'dark-green' or
              'bluish-violet', if necessary combined with
              _exptl_crystal_colour_lustre, as in 'metallic-green'.
;

data_exptl_crystal_colour_primary
    _name                      '_exptl_crystal_colour_primary'
    _category                    exptl_crystal
    _type                        char
    _list                        both
    _list_reference            '_exptl_crystal_id'
    loop_ _enumeration           colourless
                                 white
                                 black
                                 gray
                                 brown
                                 red
                                 pink
                                 orange
                                 yellow
                                 green
                                 blue
                                 violet
    _related_item              '_exptl_crystal_colour'
    _related_function            alternate
    _definition
;             The enumeration list of standardized names developed for the
              International Centre for Diffraction Data.
              The colour of a crystal is given by the combination of
              _exptl_crystal_colour_modifier with
              _exptl_crystal_colour_primary, as in 'dark-green' or
              'bluish-violet', if necessary combined with
              _exptl_crystal_colour_lustre, as in 'metallic-green'.
;

data_exptl_crystal_density_diffrn
    _name                      '_exptl_crystal_density_diffrn'
    _category                    exptl_crystal
    _type                        numb
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _enumeration_range           0.0:
    _units                       Mgm^-3^
    _units_detail              'megagrams per cubic metre'
    _definition
;              Density values calculated from the crystal cell and contents. The
               units are megagrams per cubic metre (grams per cubic centimetre).
;

data_exptl_crystal_density_meas
    _name                      '_exptl_crystal_density_meas'
    _category                    exptl_crystal
    _type                        numb
    _type_conditions             esd
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _enumeration_range           0.0:
    _units                       Mgm^-3^
    _units_detail              'megagrams per cubic metre'
    _definition
;              Density values measured using standard chemical and physical
               methods. The units are megagrams per cubic metre (grams per
               cubic centimetre).
;

data_exptl_crystal_density_meas_gt
    _name                      '_exptl_crystal_density_meas_gt'
    _category                    exptl_crystal
    _type                        numb
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _enumeration_range           0.0:
    _units                       Mg^-3^
    _units_detail              'megagrams per cubic metre'
    _related_item              '_exptl_crystal_density_meas'
    _related_function            alternate
    loop_ _example
          _example_detail
                                 2.5
;                              lower limit for the density (only the range
                               within which the density lies was given in the
                               original paper)
;
    _definition
;              The value above which the density measured using standard
               chemical and physical methods lies. The units are megagrams
               per cubic metre (grams per cubic centimetre).
               _exptl_crystal_density_meas_gt and
               _exptl_crystal_density_meas_lt should not be used to
               report new experimental work, for which
               _exptl_crystal_density_meas should be used. These items
               are intended for use in reporting information in
               existing databases and archives which would be misleading if
               reported under _exptl_crystal_density_meas.
;

data_exptl_crystal_density_meas_lt
    _name                      '_exptl_crystal_density_meas_lt'
    _category                    exptl_crystal
    _type                        numb
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _enumeration_range           0.0:
    _units                       Mg^-3^
    _units_detail              'megagrams per cubic metre'
    _related_item              '_exptl_crystal_density_meas'
    _related_function            alternate
    loop_ _example
          _example_detail
                                 1.0
                               'specimen floats in water'
                                 5.0
;                              upper limit for the density (only the range
                               within which the density lies was given in the
                               original paper)
;
    _definition
;              The value below which the density measured using standard
               chemical and physical methods lies. The units are megagrams
               per cubic metre (grams per cubic centimetre).
               _exptl_crystal_density_meas_gt and
               _exptl_crystal_density_meas_lt should not be used to
               report new experimental work, for which
               _exptl_crystal_density_meas should be used. These items
               are intended for use in reporting information in
               existing databases and archives which would be misleading if
               reported under _exptl_crystal_density_meas.
;


data_exptl_crystal_density_meas_temp
    _name                      '_exptl_crystal_density_meas_temp'
    _category                    exptl_crystal
    _type                        numb
    _type_conditions             esd
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _definition
;              Temperature in kelvins at which _exptl_crystal_density_meas
               was determined.
;

data_exptl_crystal_density_meas_temp_gt
    _name                      '_exptl_crystal_density_meas_temp_gt'
    _category                    exptl_crystal
    _type                        numb
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _related_item              '_exptl_crystal_density_meas_temp'
    _related_function            alternate
    _definition
;              Temperature in kelvins above which _exptl_crystal_density_meas
               was determined. _exptl_crystal_density_meas_temp_gt and
               _exptl_crystal_density_meas_temp_lt should not be used for
               reporting new work, for which the correct temperature of
               measurement should be given. These items are intended for
               use in reporting information stored in databases
               or archives which would be misleading if reported under
               _exptl_crystal_density_meas_temp.
;

data_exptl_crystal_density_meas_temp_lt
    _name                      '_exptl_crystal_density_meas_temp_lt'
    _category                    exptl_crystal
    _type                        numb
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _enumeration_range           0.0:
    _units                       K
    _units_detail                kelvin
    _related_item              '_exptl_crystal_density_meas_temp'
    _related_function            alternate
    loop_ _example
          _example_detail
                                 300
;                               The density was measured at some unspecified
                                temperature below room temperature.
;
    _definition
;              Temperature in kelvins below which _exptl_crystal_density_meas
               was determined. _exptl_crystal_density_meas_temp_gt and
               _exptl_crystal_density_meas_temp_lt should not be used for
               reporting new work, for which the correct temperature of
               measurement should be given. These items are intended for
               use in reporting information stored in databases
               or archives which would be misleading if reported under
               _exptl_crystal_density_meas_temp.
;

data_exptl_crystal_density_method
    _name                      '_exptl_crystal_density_method'
    _category                    exptl_crystal
    _type                        char
    _list                        both
    _list_reference            '_exptl_crystal_id'
    loop_ _example             'flotation in aqueous KI'
                               'not measured'
                               'Berman density torsion balance'

    _definition
;              The method used to measure _exptl_crystal_density_meas.
;

data_exptl_crystal_description
    _name                      '_exptl_crystal_description'
    _category                    exptl_crystal
    _type                        char
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _definition
;              A description of the quality and habit of the crystal.
               The crystal dimensions should not normally be reported here;
               use instead _exptl_crystal_size_ for the gross dimensions of
               the crystal and _exptl_crystal_face_ to describe the
               relationship between individual faces.
;

data_exptl_crystal_F_000
    _name                      '_exptl_crystal_F_000'
    _category                    exptl_crystal
    _type                        numb
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _enumeration_range           0.0:
    _definition
;              The effective number of electrons in the crystal unit cell
               contributing to F(000). This may contain dispersion contributions
               and is calculated as

               F(000) = [ (sum f~r~)^2^ + (sum f~i~)^2^ ]^1/2^

               f~r~   = real part of the scattering factors at theta = 0
               f~i~   = imaginary part of the scattering factors at theta = 0

                        the sum is taken over each atom in the unit cell
;

data_exptl_crystal_id
    _name                      '_exptl_crystal_id'
    _category                    exptl_crystal
    _type                        char
    _list                        yes
    _list_mandatory              yes
    loop_ _list_link_child     '_diffrn_refln_crystal_id'
                               '_refln_crystal_id'
    _definition
;              Code identifying each crystal if multiple crystals are used. It
               is used to link with _diffrn_refln_crystal_id in the intensity
               measurements and with _refln_crystal_id in the _refln_ list.
;

data_exptl_crystal_preparation
    _name                      '_exptl_crystal_preparation'
    _category                    exptl_crystal
    _type                        char
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _example                   'mounted in an argon-filled quartz capillary'
    _definition
;              Details of crystal growth and preparation of the crystal (e.g.
               mounting) prior to the intensity measurements.
;

data_exptl_crystal_pressure_history
    _name                      '_exptl_crystal_pressure_history'
    _category                    exptl_crystal
    _type                        char
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _definition
;              Relevant details concerning the pressure history of the
               sample.
;

data_exptl_crystal_recrystallization_method
    _name                      '_exptl_crystal_recrystallization_method'
    _category                    exptl_crystal
    _type                        char
    _definition
;              Describes the method used to recrystallize the sample.
               Sufficient details should be given for the procedure to be
               repeated.  The temperature or temperatures should be given as
               well as details of the solvent, flux or carrier gas with
               concentrations or pressures and ambient atmosphere.
;

data_exptl_crystal_size_
    loop_ _name                '_exptl_crystal_size_length'
                               '_exptl_crystal_size_max'
                               '_exptl_crystal_size_mid'
                               '_exptl_crystal_size_min'
                               '_exptl_crystal_size_rad'
    _category                    exptl_crystal
    _type                        numb
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _enumeration_range           0.0:
    _units                       mm
    _units_detail              'millimetres'
    _definition
;              The maximum, medial and minimum dimensions in millimetres of
               the crystal. If the crystal is a sphere, then the *_rad item is
               its radius. If the crystal is a cylinder, then the *_rad item
               is its radius and the *_length item is its length. These may
               appear in a list with _exptl_crystal_id if multiple crystals
               are used in the experiment.
;

data_exptl_crystal_thermal_history
    _name                      '_exptl_crystal_thermal_history'
    _category                    exptl_crystal
    _type                        char
    _list                        both
    _list_reference            '_exptl_crystal_id'
    _definition
;              Relevant details concerning the thermal history of the
               sample.
;

########################
## EXPTL_CRYSTAL_FACE ##
########################

data_exptl_crystal_face_[]
    _name                      '_exptl_crystal_face_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _exptl_crystal_face_index_h
    _exptl_crystal_face_index_k
    _exptl_crystal_face_index_l
    _exptl_crystal_face_perp_dist
         0   -1   -2    .18274
         1    0   -2    .17571
        -1    1   -2    .17845
        -2    1    0    .21010
        -1    0    2    .18849
         1   -1    2    .20605
         2   -1    0    .24680
        -1    2    0    .19688
         0    1    2    .15206
;
;
    Example 1 - based on structure PAWD2 of Vittal & Dean [Acta
                Cryst. (1996), C52, 1180-1182].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the EXPTL_CRYSTAL_FACE category record details
               of the crystal faces.
;

data_exptl_crystal_face_diffr_
    loop_ _name                '_exptl_crystal_face_diffr_chi'
                               '_exptl_crystal_face_diffr_kappa'
                               '_exptl_crystal_face_diffr_phi'
                               '_exptl_crystal_face_diffr_psi'
    _category                    exptl_crystal_face
    _type                        numb
    _list                        yes
    _list_reference            '_exptl_crystal_face_index_'
    _units                       deg
    _units_detail              'degrees'
    _definition
;              The goniometer angle settings in degrees when the perpendicular
               to the specified crystal face is aligned along a specified
               direction (e.g. the bisector of the incident and reflected beams
               in an optical goniometer).

;

data_exptl_crystal_face_index_
    loop_ _name                '_exptl_crystal_face_index_h'
                               '_exptl_crystal_face_index_k'
                               '_exptl_crystal_face_index_l'
    _category                    exptl_crystal_face
    _type                        numb
    _list                        yes
    _list_mandatory              yes
    _definition
;              Miller indices of the crystal face associated with the value
               _exptl_crystal_face_perp_dist.
;

data_exptl_crystal_face_perp_dist
    _name                      '_exptl_crystal_face_perp_dist'
    _category                    exptl_crystal_face
    _type                        numb
    _list                        yes
    _list_reference            '_exptl_crystal_face_index_'
    _enumeration_range           0.0:
    _units                       mm
    _units_detail              'millimetres'
    _definition
;              The perpendicular distance in millimetres from the face to the
               centre of rotation of the crystal.
;

##########
## GEOM ##
##########

data_geom_[]
    _name                      '_geom_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
        _geom_special_details
    ;  All esds (except the esd in the dihedral angle between
       two l.s. planes) are estimated using the full covariance
       matrix. The cell esds are taken into account individually
       in the estimation of esds in distances, angles and
       torsion angles; correlations between esds in cell
       parameters are only used when they are defined by crystal
       symmetry. An approximate (isotropic) treatment of cell
       esds is used for estimating esds involving l.s. planes.
    ;
;
;
    Example 1 - based on data set bagan of Yamane & DiSalvo [Acta
                Cryst. (1996), C52, 760-761].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the GEOM and related (GEOM_ANGLE,
               GEOM_BOND, GEOM_CONTACT, GEOM_HBOND and GEOM_TORSION)
               categories record details about the molecular and crystal
               geometry as calculated from the ATOM,
               CELL and SYMMETRY data.

               Geometry data are usually redundant, in that they can be
               calculated from other more fundamental quantities in the data
               block. However, they serve the dual purposes of providing a
               check on the correctness of both sets of data and of enabling
               the most important geometric data to be identified for
               publication by setting the appropriate publication flag.
;

data_geom_special_details
    _name                      '_geom_special_details'
    _category                    geom
    _type                        char
    _definition
;              The description of geometrical information not covered by the
               existing data names in the geometry categories, such as
               least-squares planes.
;

################
## GEOM_ANGLE ##
################

data_geom_angle_[]
    _name                      '_geom_angle_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _geom_angle_atom_site_label_1
    _geom_angle_atom_site_label_2
    _geom_angle_atom_site_label_3
    _geom_angle
    _geom_angle_site_symmetry_1
    _geom_angle_site_symmetry_2
    _geom_angle_site_symmetry_3
    _geom_angle_publ_flag
     C2  O1  C5   111.6(2)  1_555  1_555  1_555  yes
     O1  C2  C3   110.9(2)  1_555  1_555  1_555  yes
     O1  C2  O21  122.2(3)  1_555  1_555  1_555  yes
     C3  C2  O21  127.0(3)  1_555  1_555  1_555  yes
     C2  C3  N4   101.3(2)  1_555  1_555  1_555  yes
     C2  C3  C31  111.3(2)  1_555  1_555  1_555  yes
     C2  C3  H3   107(1)    1_555  1_555  1_555  no
     N4  C3  C31  116.7(2)  1_555  1_555  1_555  yes
    # - - - - data truncated for brevity - - - -
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the GEOM_ANGLE category record details about the
               bond angles as calculated from the ATOM,
               CELL and SYMMETRY data.
;

data_geom_angle
    _name                      '_geom_angle'
    _category                    geom_angle
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_geom_angle_atom_site_label_'
    _units                       deg
    _units_detail              'degrees'
    _definition
;              Angle in degrees defined by the three sites
               _geom_angle_atom_site_label_1, *_2 and *_3. The site at *_2
               is at the apex of the angle.
;

data_geom_angle_atom_site_label_
    loop_ _name                '_geom_angle_atom_site_label_1'
                               '_geom_angle_atom_site_label_2'
                               '_geom_angle_atom_site_label_3'
    _category                    geom_angle
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_parent          '_atom_site_label'
    _definition
;              The labels of the three atom sites which define the angle
               given by _geom_angle. These must match labels specified as
               _atom_site_label in the atom list. Label 2 identifies the site at
               the apex of the angle.
;

data_geom_angle_publ_flag
    _name                      '_geom_angle_publ_flag'
    _category                    geom_angle
    _type                        char
    _list                        yes
    _list_reference            '_geom_angle_atom_site_label_'
    loop_ _enumeration
          _enumeration_detail    no  'do not include angle in special list'
                                 n   'abbreviation for "no"'
                                 yes 'do include angle in special list'
                                 y   'abbreviation for "yes"'
    _enumeration_default         no
    _definition
;              This code signals whether the angle is referred to in a
               publication or should be placed in a table of significant
               angles.
;

data_geom_angle_site_symmetry_
    loop_ _name                '_geom_angle_site_symmetry_1'
                               '_geom_angle_site_symmetry_2'
                               '_geom_angle_site_symmetry_3'
    _category                    geom_angle
    _type                        char
    _list                        yes
    _list_reference            '_geom_angle_atom_site_label_'
    loop_ _example
          _example_detail        .     'no symmetry or translation to site'
                                 4     '4th symmetry operation applied'
                                 7_645 '7th symm. posn.; +a on x; -b on y'
    _definition
;              The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _space_group_symop_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry-transformed coordinates to generate
               the atom used in calculating the angle. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

###############
## GEOM_BOND ##
###############

data_geom_bond_[]
    _name                      '_geom_bond_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _geom_bond_atom_site_label_1
    _geom_bond_atom_site_label_2
    _geom_bond_distance
    _geom_bond_site_symmetry_1
    _geom_bond_site_symmetry_2
    _geom_bond_publ_flag
      O1  C2   1.342(4)  1_555  1_555  yes
      O1  C5   1.439(3)  1_555  1_555  yes
      C2  C3   1.512(4)  1_555  1_555  yes
      C2  O21  1.199(4)  1_555  1_555  yes
      C3  N4   1.465(3)  1_555  1_555  yes
      C3  C31  1.537(4)  1_555  1_555  yes
      C3  H3   1.00(3)   1_555  1_555  no
      N4  C5   1.472(3)  1_555  1_555  yes
    # - - - - data truncated for brevity - - - -
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _geom_bond_atom_site_label_1
    _geom_bond_atom_site_label_2
    _geom_bond_distance
    _geom_bond_multiplicity
    Ca1   F1   2.495(9)    1
    Ca1   F2   2.291(10)   2
    Ca1   F2   2.391(11)   2
    Ca1   F3   2.214(11)   2
    Cr1   F1   1.940(11)   2
    Cr1   F2   1.918(9)    2
    Cr1   F3   1.848(10)   2
;
;
    Example 2 - An example showing a listing of only symmetry-unique bonds.
                In high-symmetry structures when many bonds are related by
                symmetry, it may not be necessary or desirable to list all
                the bonds in the environment of the first named atom. Some
                users may wish to give only the symmetry-independent
                distances and supply a multiplicity to indicate how many
                such bonds are found in the atomic environment.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _geom_bond_atom_site_label_1
    _geom_bond_atom_site_label_2
    _geom_bond_site_symmetry_2
    _geom_bond_distance
    _geom_bond_multiplicity
    Ca1   F1   1_555  2.495(9)    1
    Ca1   F2   1_555  2.291(10)   2
    Ca1   F2   2_555  2.291(10)   0
    Ca1   F2   3_565  2.391(11)   2
    Ca1   F2   4_555  2.391(11)   0
    Ca1   F3   2_545  2.214(11)   2
    Ca1   F3   5_555  2.214(11)   0
    Cr1   F1   1_555  1.940(11)   2
    Cr1   F1   2_555  1.940(11)   0
    Cr1   F2   1_555  1.918(9)    2
    Cr1   F2   2_555  1.918(9)    0
    Cr1   F3   1_555  1.848(10)   2
    Cr1   F3   2_555  1.848(10)   0
;
;
    Example 3 - The same structure as in Example 2, but where the
                multiplicity is given with a full bond list. Note the
                use of a value of 0 for _geom_bond_multiplicity in
                such a case.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the GEOM_BOND category record details about
               bonds as calculated from the ATOM, CELL
               and SYMMETRY data.
;

data_geom_bond_atom_site_label_
    loop_ _name                '_geom_bond_atom_site_label_1'
                               '_geom_bond_atom_site_label_2'
    _category                    geom_bond
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_parent          '_atom_site_label'
    _definition
;              The labels of two atom sites that form a bond. These must match
               labels specified as _atom_site_label in the atom list.
;

data_geom_bond_distance
    _name                      '_geom_bond_distance'
    _category                    geom_bond
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_geom_bond_atom_site_label_'
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The intramolecular bond distance in angstroms.
;

data_geom_bond_multiplicity
    _name                      '_geom_bond_multiplicity'
    _category                    geom_bond        
    _type                        numb        
    _list                        yes        
    _list_reference            '_geom_bond_atom_site_label_'    
    _enumeration_range           0:
    _enumeration_default         1
    _definition
;              The number of times the given bond appears in the environment
               of the atoms labelled _geom_bond_atom_site_label_1. In cases
               where the full list of bonds is given, one of the series of
               equivalent bonds may be assigned the appropriate multiplicity
               while the others are assigned a value of 0.
;

data_geom_bond_publ_flag
    _name                      '_geom_bond_publ_flag'
    _category                    geom_bond
    _type                        char
    _list                        yes
    _list_reference            '_geom_bond_atom_site_label_'
    loop_ _enumeration
          _enumeration_detail    no  'do not include bond in special list'
                                 n   'abbreviation for "no"'
                                 yes 'do include bond in special list'
                                 y   'abbreviation for "yes"'
    _enumeration_default         no
    _definition
;              This code signals whether the bond distance is referred to in a
               publication or should be placed in a list of significant bond
               distances.
;

data_geom_bond_site_symmetry_
    loop_ _name                '_geom_bond_site_symmetry_1'
                               '_geom_bond_site_symmetry_2'
    _category                    geom_bond
    _type                        char
    _list                        yes
    _list_reference            '_geom_bond_atom_site_label_'
    loop_ _example
          _example_detail        .     'no symmetry or translation to site'
                                 4     '4th symmetry operation applied'
                                 7_645 '7th symm. posn.; +a on x; -b on y'
    _definition
;              The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _space_group_symop_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry-transformed coordinates to generate
               the atom used in calculating the bond. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

data_geom_bond_valence
    _name                      '_geom_bond_valence'
    _category                    geom_bond
    _type                        numb
    _list                        yes
    _list_reference            '_geom_bond_atom_site_label_'
    _definition
;              The bond valence calculated from _geom_bond_distance.
;


##################
## GEOM_CONTACT ##
##################

data_geom_contact_[]
    _name                      '_geom_contact_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
     _geom_contact_atom_site_label_1
     _geom_contact_atom_site_label_2
     _geom_contact_distance
     _geom_contact_site_symmetry_1
     _geom_contact_site_symmetry_2
     _geom_contact_publ_flag
     O(1)  O(2)     2.735(3)  .  .  yes
     H(O1) O(2)     1.82      .  .  no
;
;
    Example 1 - based on data set CLPHO6 of Ferguson, Ruhl, McKervey & Browne
                [Acta Cryst. (1992), C48, 2262-2264].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the GEOM_CONTACT category record details about
               interatomic contacts as calculated from the
               ATOM, CELL and SYMMETRY data.
;

data_geom_contact_atom_site_label_
    loop_ _name                '_geom_contact_atom_site_label_1'
                               '_geom_contact_atom_site_label_2'
    _category                    geom_contact
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_parent          '_atom_site_label'
    _definition
;              The labels of two atom sites that are within contact distance.
               The labels must match _atom_site_label codes in the atom list.
;

data_geom_contact_distance
    _name                      '_geom_contact_distance'
    _category                    geom_contact
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_geom_contact_atom_site_label_'
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The interatomic contact distance in angstroms.
;

data_geom_contact_publ_flag
    _name                      '_geom_contact_publ_flag'
    _category                    geom_contact
    _type                        char
    _list                        yes
    _list_reference            '_geom_contact_atom_site_label_'
    loop_ _enumeration
          _enumeration_detail    no  'do not include distance in special list'
                                 n   'abbreviation for "no"'
                                 yes 'do include distance in special list'
                                 y   'abbreviation for "yes"'
    _enumeration_default         no
    _definition
;              This code signals whether the contact distance is referred to
               in a publication or should be placed in a list of significant
               contact distances.
;

data_geom_contact_site_symmetry_
    loop_ _name                '_geom_contact_site_symmetry_1'
                               '_geom_contact_site_symmetry_2'
    _category                    geom_contact
    _type                        char
    _list                        yes
    _list_reference            '_geom_contact_atom_site_label_'
    loop_ _example
          _example_detail        .     'no symmetry or translation to site'
                                 4     '4th symmetry operation applied'
                                 7_645 '7th symm. posn.; +a on x; -b on y'
    _definition
;              The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _space_group_symop_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry-transformed coordinates to generate
               the atom used in calculating the contact. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

################
## GEOM_HBOND ##
################

data_geom_hbond_[]
    _name                      '_geom_hbond_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _geom_hbond_atom_site_label_D
    _geom_hbond_atom_site_label_H
    _geom_hbond_atom_site_label_A
    _geom_hbond_distance_DH
    _geom_hbond_distance_HA
    _geom_hbond_distance_DA
    _geom_hbond_angle_DHA
    _geom_hbond_publ_flag

    N6   HN6  OW   0.888(8)  1.921(12)  2.801(8)  169.6(8)  yes
    OW   HO2  O7   0.917(6)  1.923(12)  2.793(8)  153.5(8)  yes
    OW   HO1  N10  0.894(8)  1.886(11)  2.842(8)  179.7(9)  yes
;
;
    Example 1 - based on C~14~H~13~ClN~2~O.H~2~O, reported by Palmer,
                Puddle & Lisgarten [Acta Cryst. (1993), C49, 1777-1779].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the GEOM_HBOND category record details about
               hydrogen bonds as calculated from the ATOM,
               CELL and SYMMETRY data.
;

data_geom_hbond_angle_DHA
    _name                      '_geom_hbond_angle_DHA'
    _category                    geom_hbond
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_geom_hbond_atom_site_label_'
    _units                       deg
    _units_detail              'degrees'
    _definition
;              Angle in degrees defined by the three sites
               _geom_hbond_atom_site_label_D, *_H and *_A. The site at *_H
               (the hydrogen atom participating in the interaction) is at
               the apex of the angle.
;

data_geom_hbond_atom_site_label_
    loop_ _name                '_geom_hbond_atom_site_label_D'
                               '_geom_hbond_atom_site_label_H'
                               '_geom_hbond_atom_site_label_A'
    _category                    geom_hbond
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_parent          '_atom_site_label'
    _definition
;              The labels of three atom sites (respectively, the donor atom,
               hydrogen atom and acceptor atom) participating in a hydrogen
               bond. These must match labels specified as _atom_site_label
               in the atom list.
;

data_geom_hbond_distance_
    loop_ _name                '_geom_hbond_distance_DH'
                               '_geom_hbond_distance_HA'
                               '_geom_hbond_distance_DA'
    _category                    geom_hbond
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_geom_hbond_atom_site_label_'
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              Distances in angstroms between the donor and hydrogen (*_DH),
               hydrogen and acceptor (*_HA) and donor and acceptor (*_DA)
               sites in a hydrogen bond.
;

data_geom_hbond_publ_flag
    _name                      '_geom_hbond_publ_flag'
    _category                    geom_hbond
    _type                        char
    _list                        yes
    _list_reference            '_geom_hbond_atom_site_label_'
    loop_ _enumeration
          _enumeration_detail    no  'do not include bond in special list'
                                 n   'abbreviation for "no"'
                                 yes 'do include bond in special list'
                                 y   'abbreviation for "yes"'
    _enumeration_default         no
    _definition
;              This code signals whether the hydrogen-bond information
               is referred to in a publication or should be placed in a
               table of significant hydrogen-bond geometry.
;

data_geom_hbond_site_symmetry_
    loop_ _name                '_geom_hbond_site_symmetry_D'
                               '_geom_hbond_site_symmetry_H'
                               '_geom_hbond_site_symmetry_A'
    _category                    geom_hbond
    _type                        char
    _list                        yes
    _list_reference            '_geom_hbond_atom_site_label_'
    loop_ _example
          _example_detail        .     'no symmetry or translation to site'
                                 4     '4th symmetry operation applied'
                                 7_645 '7th symm. posn.; +a on x; -b on y'
    _definition
;              The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _space_group_symop_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry-transformed coordinates to generate
               the atom used in calculating the hydrogen bond. These
               translations (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

##################
## GEOM_TORSION ##
##################

data_geom_torsion_[]
    _name                      '_geom_torsion_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
     _geom_torsion_atom_site_label_1
     _geom_torsion_atom_site_label_2
     _geom_torsion_atom_site_label_3
     _geom_torsion_atom_site_label_4
     _geom_torsion
     _geom_torsion_site_symmetry_1
     _geom_torsion_site_symmetry_2
     _geom_torsion_site_symmetry_3
     _geom_torsion_site_symmetry_4
     _geom_torsion_publ_flag
     C(9)  O(2)  C(7)   C(2)    71.8(2)  .  .  .  .      yes
     C(7)  O(2)  C(9)   C(10) -168.0(3)  .  .  .  2_666  yes
     C(10) O(3)  C(8)   C(6)  -167.7(3)  .  .  .  .      yes
     C(8)  O(3)  C(10)  C(9)   -69.7(2)  .  .  .  2_666  yes
     O(1)  C(1)  C(2)   C(3)  -179.5(4)  .  .  .  .      no
     O(1)  C(1)  C(2)   C(7)    -0.6(1)  .  .  .  .      no
;
;
     Example 1 - based on data set CLPHO6 of Ferguson, Ruhl, McKervey & Browne
                [Acta Cryst. (1992), C48, 2262-2264].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the GEOM_TORSION category record details about
               interatomic torsion angles as calculated from
               the ATOM, CELL and SYMMETRY data.
;

data_geom_torsion
    _name                      '_geom_torsion'
    _category                    geom_torsion
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_geom_torsion_atom_site_label_'
    _units                       deg
    _units_detail              'degrees'
    _definition
;              The torsion angle in degrees bounded by the four atom sites
               identified by the _geom_torsion_atom_site_label_ codes. These
               must match labels specified as _atom_site_label in the atom list.
               The torsion-angle definition should be that of Klyne and Prelog.

               Ref: Klyne, W. & Prelog, V. (1960). Experientia, 16, 521-523.
;

data_geom_torsion_atom_site_label_
    loop_ _name                '_geom_torsion_atom_site_label_1'
                               '_geom_torsion_atom_site_label_2'
                               '_geom_torsion_atom_site_label_3'
                               '_geom_torsion_atom_site_label_4'
    _category                    geom_torsion
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_parent          '_atom_site_label'
    _definition
;              The labels of the four atom sites which define the torsion angle
               specified by _geom_torsion. These must match codes specified as
               _atom_site_label in the atom list. The torsion-angle definition
               should be that of Klyne and Prelog. The vector direction
               *_label_2 to *_label_3 is the viewing direction, and the torsion
               angle is the angle of twist required to superimpose the
               projection of the vector between site 2 and site 1 onto the
               projection of the vector between site 3 and site 4. Clockwise
               torsions are positive, anticlockwise torsions are negative.

               Ref: Klyne, W. & Prelog, V. (1960). Experientia, 16, 521-523.
;

data_geom_torsion_publ_flag
    _name                      '_geom_torsion_publ_flag'
    _category                    geom_torsion
    _type                        char
    _list                        yes
    _list_reference            '_geom_torsion_atom_site_label_'
    loop_ _enumeration
          _enumeration_detail    no  'do not include angle in special list'
                                 n   'abbreviation for "no"'
                                 yes 'do include angle in special list'
                                 y   'abbreviation for "yes"'
    _enumeration_default         no
    _definition
;              This code signals whether the torsion angle is referred to in a
               publication or should be placed in a table of significant
               torsion angles.
;

data_geom_torsion_site_symmetry_
    loop_ _name                '_geom_torsion_site_symmetry_1'
                               '_geom_torsion_site_symmetry_2'
                               '_geom_torsion_site_symmetry_3'
                               '_geom_torsion_site_symmetry_4'
    _category                    geom_torsion
    _type                        char
    _list                        yes
    _list_reference            '_geom_torsion_atom_site_label_'
    loop_ _example
          _example_detail        .     'no symmetry or translation to site'
                                 4     '4th symmetry operation applied'
                                 7_645 '7th symm. posn.; +a on x; -b on y'
    _definition
;              The symmetry code of each atom site as the symmetry-equivalent
               position number 'n' and the cell translation number 'klm'.
               These numbers are combined to form the code 'n klm' or n_klm.
               The character string n_klm is composed as follows:

               n refers to the symmetry operation that is applied to the
               coordinates stored in _atom_site_fract_x, _atom_site_fract_y
               and _atom_site_fract_z. It must match a number given in
               _space_group_symop_id.

               k, l and m refer to the translations that are subsequently
               applied to the symmetry-transformed coordinates to generate
               the atom used in calculating the angle. These translations
               (x,y,z) are related to (k,l,m) by the relations
                    k = 5 + x
                    l = 5 + y
                    m = 5 + z
               By adding 5 to the translations, the use of negative numbers
               is avoided.
;

#############
## JOURNAL ##
#############

data_journal_[]
    _name                      '_journal_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _journal_date_recd_electronic     91-04-15
    _journal_date_from_coeditor       91-04-18
    _journal_date_accepted            91-04-18
    _journal_date_printers_first      91-08-07
    _journal_date_proofs_out          91-08-07
    _journal_coeditor_code            HL0007
    _journal_techeditor_code          C910963
    _journal_coden_ASTM               ACSCEE
    _journal_name_full        'Acta Crystallographica Section C'
    _journal_year                     1991
    _journal_volume                   47
    _journal_issue                    NOV91
    _journal_page_first               2276
    _journal_page_last                2277
;
;
    Example 1 - based on Acta Cryst. file for entry HL0007 [Willis, Beckwith
                & Tozer (1991). Acta Cryst. C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the JOURNAL category record details about the
               book-keeping by the journal staff when processing
               a CIF submitted for publication.

               The creator of a CIF will not normally specify these data items.
               The data names are not defined in the dictionary because they are
               for journal use only.
;

data_journal_
    loop_ _name                '_journal_coden_ASTM'
                               '_journal_coden_Cambridge'
                               '_journal_coeditor_address'
                               '_journal_coeditor_code'
                               '_journal_coeditor_email'
                               '_journal_coeditor_fax'
                               '_journal_coeditor_name'
                               '_journal_coeditor_notes'
                               '_journal_coeditor_phone'
                               '_journal_data_validation_number'
                               '_journal_date_accepted'
                               '_journal_date_from_coeditor'
                               '_journal_date_to_coeditor'
                               '_journal_date_printers_final'
                               '_journal_date_printers_first'
                               '_journal_date_proofs_in'
                               '_journal_date_proofs_out'
                               '_journal_date_recd_copyright'
                               '_journal_date_recd_electronic'
                               '_journal_date_recd_hard_copy'
                               '_journal_issue'
                               '_journal_language'
                               '_journal_name_full'
                               '_journal_page_first'
                               '_journal_page_last'
                               '_journal_paper_category'
                               '_journal_suppl_publ_number'
                               '_journal_suppl_publ_pages'
                               '_journal_techeditor_address'
                               '_journal_techeditor_code'
                               '_journal_techeditor_email'
                               '_journal_techeditor_fax'
                               '_journal_techeditor_name'
                               '_journal_techeditor_notes'
                               '_journal_techeditor_phone'
                               '_journal_volume'
                               '_journal_year'
    _category                    journal
    _type                        char
    _definition
;              Data items specified by the journal staff.
;

###################
## JOURNAL_INDEX ##
###################

data_journal_index_[]
    _name                      '_journal_index_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _journal_index_type
    _journal_index_term
    _journal_index_subterm
      O   C16H19NO4            .
      S   alkaloids           (-)-norcocaine
      S   (-)-norcocaine       .
      S
    ;  [2R,3S-(2\b,3\b)]-methyl
       3-(benzoyloxy)-8-azabicyclo[3.2.1]octane-2-carboxylate
    ;                          .
;
;
    Example 1 - based on a paper by Zhu, Reynolds, Klein & Trudell
                [Acta Cryst. (1994), C50, 2067-2069].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the JOURNAL_INDEX category are used to list
               terms used to generate the journal indexes.

               The creator of a CIF will not normally specify these data items.
;

data_journal_index_
    loop_ _name                '_journal_index_subterm'
                               '_journal_index_term'
                               '_journal_index_type'
    _category                    journal_index
    _type                        char
    _definition
;             Indexing terms supplied by the journal staff.
;

##########
## PUBL ##
##########

data_publ_[]
    _name                      '_publ_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;    _publ_section_title
    ;  trans-3-Benzoyl-2-(tert-butyl)-4-(iso-butyl)-
       1,3-oxazolidin-5-one
    ;

    _publ_section_abstract
    ;  The oxazolidinone ring is a shallow envelope
       conformation with the tert-butyl and iso-butyl groups
       occupying trans-positions with respect to the ring. The
       angles at the N atom sum to 356.2\%, indicating a very
       small degree of pyramidalization at this atom. This is
       consistent with electron delocalization between the N
       atom and the carbonyl centre [N-C=O = 1.374(3)\%A].
    ;
;
;
    Example 1 - based on Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;    _publ_section_title
    ;  Hemiasterlin methyl ester
    ;

    _publ_section_title_footnote
    ;  IUPAC name: methyl 2,5-dimethyl-4-{2-[3-methyl-
       2-methylamino-3-(N-methylbenzo[b]pyrrol-
       3-yl)butanamido]-3,3-dimethyl-N-methyl-
       butanamido}-2-hexenoate.
    ;
;
;
    Example 2 - based on C~31~H~48~N~4~O~4~, reported by Coleman, Patrick,
                Andersen & Rettig [Acta Cryst. (1996), C52, 1525-1527].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the PUBL category are used when submitting a
               manuscript for publication. They refer either to the paper as
               a whole, or to specific named elements within a paper (such as
               the title and abstract, or the Comment and Experimental
               sections of Acta Crystallographica Section C). The data items
               in the PUBL_BODY category should be used for the text
               of other submissions. Typically, each journal will
               supply a list of the specific items it requires in its Notes
               for Authors.
;

data_publ_contact_author
    _name                      '_publ_contact_author'
    _category                    publ
    _type                        char
     loop_
    _example
;                       Professor George Ferguson
                        Department of Chemistry and Biochemistry
                        University of Guelph
                        Ontario
                        Canada
                        N1G 2W1
;
    _definition
;              The name and address of the author submitting the manuscript and
               data block. This is the person contacted by the journal
               editorial staff. It is preferable to use the separate data items
               _publ_contact_author_name and _publ_contact_author_address.
;

data_publ_contact_author_address
    _name                      '_publ_contact_author_address'
    _category                    publ
    _type                        char
    _example
;                       Department of Chemistry and Biochemistry
                        University of Guelph
                        Ontario
                        Canada
                        N1G 2W1
;
    _definition
;              The address of the author submitting the manuscript and
               data block. This is the person contacted by the journal
               editorial staff.
;

data_publ_contact_author_email
    _name                      '_publ_contact_author_email'
    _category                    publ
    _type                        char
    loop_ _example               name@host.domain.country
                                 bm@iucr.org
    _definition
;              E-mail address in a form recognizable to international networks.
               The format of e-mail addresses is given in Section 3.4, Address 
               Specification, of  Internet Message Format, RFC 2822, P. Resnick 
               (Editor), Network Standards Group, April 2001.
;

data_publ_contact_author_fax
    _name                      '_publ_contact_author_fax'
    _category                    publ
    _type                        char
     loop_
    _example                    '12(34)9477334'
                                '12()349477334'
    _definition
;              Facsimile telephone number of the author submitting the
               manuscript and data block.

               The recommended style is the international dialing
               prefix, followed  by the area code in parentheses, followed by
               the local number with no spaces. The earlier convention of
               including the international dialing prefix in parentheses is
               no longer recommended.
;

data_publ_contact_author_id_iucr
    _name                      '_publ_contact_author_id_iucr'
    _category                    publ
    _type                        char
    _example                     2985
    _definition
;              Identifier in the IUCr contact database of the author
               submitting the manuscript and data block. This identifier may
               be available from the World Directory of Crystallographers
               (http://wdc.iucr.org).
;

data_publ_contact_author_name
    _name                      '_publ_contact_author_name'
    _category                    publ
    _type                        char
    _example                    'Professor George Ferguson'
    _definition
;              The name of the author submitting the manuscript and
               data block. This is the person contacted by the journal
               editorial staff.
;

data_publ_contact_author_phone
    _name                      '_publ_contact_author_phone'
    _category                    publ
    _type                        char
     loop_
    _example                    '12(34)9477330'
                                '12()349477330'
                                '12(34)9477330x5543'
    _definition
;              Telephone number of the author submitting the manuscript and
               data block.

               The recommended style is the international dialing
               prefix, followed by the area code in parentheses, followed by the
               local number and any extension number prefixed by 'x',
               with no spaces. The earlier convention of including
               the international dialing prefix in parentheses is no longer
               recommended.
;

data_publ_contact_letter
    _name                      '_publ_contact_letter'
    _category                    publ
    _type                        char
    _definition
;              A letter submitted to the journal editor by the contact author.
;

data_publ_manuscript_creation
    _name                      '_publ_manuscript_creation'
    _category                    publ
    _type                        char
    _example                    'Tex file created by FrameMaker on a Sun 3/280'
    _definition
;              A description of the word-processor package and computer used to
               create the word-processed manuscript stored as
               _publ_manuscript_processed.
;

data_publ_manuscript_processed
    _name                      '_publ_manuscript_processed'
    _category                    publ
    _type                        char
    _definition
;              The full manuscript of a paper (excluding possibly the figures
               and the tables) output in ASCII characters from a word processor.
               Information about the generation of this data item must be
               specified in the data item _publ_manuscript_creation.
;

data_publ_manuscript_text
    _name                      '_publ_manuscript_text'
    _category                    publ
    _type                        char
    _definition
;              The full manuscript of a paper (excluding figures and possibly
               the tables) output as standard ASCII text.
;

data_publ_requested_category
    _name                      '_publ_requested_category'
    _category                    publ
    _type                        char
    loop_ _enumeration
          _enumeration_detail
            FA  'Full article'
            FI  'Full submission - inorganic (Acta C)'
            FO  'Full submission - organic (Acta C)'
            FM  'Full submission - metal-organic (Acta C)'
            CI  'CIF-access paper - inorganic (Acta C) (no longer in use)'
            CO  'CIF-access paper - organic (Acta C)  (no longer in use)'
            CM  'CIF-access paper - metal-organic (Acta C) (no longer in use)'
            EI  'Electronic submission - inorganic (Acta E)'
            EO  'Electronic submission - organic (Acta E)'
            EM  'Electronic submission - metal-organic (Acta E)'
            QI  'Inorganic compounds (Acta E)'
            QO  'Organic compounds (Acta E)'
            QM  'Metal-organic compounds (Acta E)'
            AD  'Addenda and Errata (Acta C, Acta E)'
            SC  'Short communication'
    _enumeration_default         FA
    _definition
;              The category of paper submitted. For submission to Acta
               Crystallographica Section C or Acta Crystallographica
               Section E, ONLY those codes indicated for use with those
               journals should be used.
;

data_publ_requested_coeditor_name
    _name                      '_publ_requested_coeditor_name'
    _category                    publ
    _type                        char
    _definition
;              The name of the co-editor whom the authors would like to
               handle the submitted manuscript.
;

data_publ_requested_journal
    _name                      '_publ_requested_journal'
    _category                    publ
    _type                        char
    _definition
;              The name of the journal to which the manuscript is being
               submitted.
;

data_publ_section_
    loop_ _name                '_publ_section_title'
                               '_publ_section_title_footnote'
                               '_publ_section_synopsis'
                               '_publ_section_abstract'
                               '_publ_section_comment'
                               '_publ_section_introduction'
                               '_publ_section_experimental'
                               '_publ_section_exptl_prep'
                               '_publ_section_exptl_refinement'
                               '_publ_section_exptl_solution'
                               '_publ_section_discussion'
                               '_publ_section_acknowledgements'
                               '_publ_section_references'
                               '_publ_section_related_literature'
                               '_publ_section_figure_captions'
                               '_publ_section_table_legends'
                               '_publ_section_keywords'
    _category                    publ
    _type                        char
    _definition
;              The sections of a manuscript if submitted in parts. As
               an alternative, see _publ_manuscript_text and
               _publ_manuscript_processed.

               The _publ_section_exptl_prep, _publ_section_exptl_refinement
               and _publ_section_exptl_solution items are preferred for
               separating the chemical preparation, refinement and structure
               solution aspects of the experimental description.
;

#################
## PUBL_AUTHOR ##
#################

data_publ_author_[]
    _name                      '_publ_author_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _publ_author_name
    _publ_author_address

         'Willis, Anthony C.'
    ;    Research School of Chemistry
         Australian National University
         GPO Box 4
         Canberra, ACT
         Australia    2601
    ;
;
;
    Example 1 - based on Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the PUBL_AUTHOR category record details of
               the authors of a manuscript submitted for publication.
;

data_publ_author_address
    _name                      '_publ_author_address'
    _category                    publ_author
    _type                        char
    _list                        both
    _list_reference            '_publ_author_name'
    _example
;                       Department
                        Institute
                        Street
                        City and postcode
                        COUNTRY
;
    _definition
;              The address of a publication author. If there is more than one
               author, this will be looped with _publ_author_name.
;
data_publ_author_email
    _name                      '_publ_author_email'
    _category                    publ_author
    _type                        char
    _list                          both
    _list_reference            '_publ_author_name'
    loop_ _example               name@host.domain.country
                                 bm@iucr.org
    _definition
;              The e-mail address of a publication author. If there is more 
               than one author, this will be looped with _publ_author_name.
               The format of e-mail addresses is given in Section 3.4, Address 
               Specification, of  Internet Message Format, RFC 2822, P. Resnick 
               (Editor), Network Standards Group, April 2001.
;

data_publ_author_footnote
    _name                      '_publ_author_footnote'
    _category                    publ_author
    _type                        char
    _list                        both
    _list_reference            '_publ_author_name'
    loop_ _example              'On leave from U. Western Australia'
                                'Also at Department of Biophysics'
    _definition
;              A footnote accompanying an author's name in the list of authors
               of a paper. Typically indicates sabbatical address, additional
               affiliations or date of decease.
;

data_publ_author_id_iucr
    _name                      '_publ_author_id_iucr'
    _category                    publ_author
    _type                        char
    _list                        both
    _example                     2985
    _definition
;              Identifier in the IUCr contact database of a publication
               author.  This identifier may be available from the World
               Directory of Crystallographers (http://wdc.iucr.org).
;

data_publ_author_name
    _name                      '_publ_author_name'
    _category                    publ_author
    _type                        char
    _list                        both
    _list_mandatory              yes
    loop_ _example             'Bleary, Percival R.'
                               "O'Neil, F.K."
                               'Van den Bossche, G.'
                               'Yang, D.-L.'
                               'Simonov, Yu.A.'
                               'M\"uller, H.A.'
                               'Ross II, C.R.'
    _definition
;              The name of a publication author. If there are multiple authors,
               this will be looped with _publ_author_address. The family
               name(s), followed by a comma and including any dynastic
               components, precedes the first names or initials.
;

###############
## PUBL_BODY ##
###############

data_publ_body_[]
    _name                      '_publ_body_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _publ_body_element
    _publ_body_label
    _publ_body_title
    _publ_body_format
    _publ_body_contents

         section   1         Introduction                    cif
    ; X-ray diffraction from a crystalline material provides
      information on the thermally and spatially averaged
      electron density in the crystal...
    ;
         section   2         Theory                           tex
    ; In the rigid-atom approximation, the dynamic electron
      density of an atom is described by the convolution
      product of the static atomic density and a probability
      density function,
      $\rho_{dyn}(\bf r) = \rho_{stat}(\bf r) * P(\bf r). \eqno(1)$
    ;
;
;
    Example 1 - based on a paper by R. Restori & D. Schwarzenbach
                [Acta Cryst. (1996), A52, 369-378].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _publ_body_element
    _publ_body_label
    _publ_body_title
    _publ_body_contents

         section     3
    ; The two-channel method for retrieval of the deformation
      electron density
    ;
         .
         subsection  3.1  'The two-channel entropy S[\D\r(r)]'
    ; As the wide dynamic range involved in the total electron
      density...
    ;
         subsection  3.2
    'Uniform vs informative prior model densities'        .
         subsubsection  3.2.1  'Use of uniform models'
    ; Straightforward algebra leads to expressions analogous
      to...
    ;
;
;
    Example 2 - based on a paper by R. J. Papoular, Y. Vekhter & P. Coppens
                [Acta Cryst. (1996), A52, 397-407].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the PUBL_BODY category permit the labelling of
               different text sections within the body of a paper.
               Note that these should not be used in a paper which has
               a standard format with sections tagged by specific data names
               (such as in Acta Crystallographica Section C). Typically,
               each journal will supply a list of the specific items it
               requires in its Notes for Authors.
;

data_publ_body_contents
    _name                      '_publ_body_contents'
    _category                    publ_body
    _type                        char
    _list                        yes
    _list_reference            '_publ_body_label'
    _definition
;              A text section of a paper.
;

data_publ_body_element
    _name                      '_publ_body_element'
    _category                    publ_body
    _type                        char
    _list                        yes
    _list_reference            '_publ_body_label'
    loop_ _enumeration
                                 section
                                 subsection
                                 subsubsection
                                 appendix
                                 footnote
    _definition
;              The functional role of the associated text section.
;

data_publ_body_format
    _name                      '_publ_body_format'
    _category                    publ_body
    _type                        char
    _list                        yes
    _list_reference            '_publ_body_label'
    loop_ _enumeration
          _enumeration_detail
                                 ascii   'no coding for special symbols'
                                 cif     'CIF convention'
                                 latex   'LaTeX'
                                 rtf     'Rich Text Format'
                                 sgml    'SGML (ISO 8879)'
                                 tex     'TeX'
                                 troff   'troff or nroff'
    _enumeration_default         cif
    _definition
;              Code indicating the appropriate typesetting conventions
               for accented characters and special symbols in the text
               section.
;

data_publ_body_label
    _name                      '_publ_body_label'
    _category                    publ_body
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_uniqueness           '_publ_body_element'
    loop_ _example               1   1.1   2.1.3
    _definition
;              Code identifying the section of text. The combination of this
               with _publ_body_element must be unique.
;

data_publ_body_title
    _name                      '_publ_body_title'
    _category                    publ_body
    _type                        char
    _list                        yes
    _list_reference            '_publ_body_label'
    _definition
;              Title of the associated section of text.
;

##########################
## PUBL_MANUSCRIPT_INCL ##
##########################

data_publ_manuscript_incl_[]
    _name                      '_publ_manuscript_incl_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _publ_manuscript_incl_extra_item
    _publ_manuscript_incl_extra_info
    _publ_manuscript_incl_extra_defn
    #
    # Include Hydrogen Bonding Geometry Description
    # =============================================
    # Name                             explanation    standard?
    # ----                             -----------    ---------
      '_geom_hbond_atom_site_label_D'  'H-bond donor'     yes
      '_geom_hbond_atom_site_label_H'  'H-bond hydrogen'  yes
      '_geom_hbond_atom_site_label_A'  'H-bond acceptor'  yes
      '_geom_hbond_distance_DH'        'H-bond D-H'       yes
      '_geom_hbond_distance_HA'        'H-bond H...A'     yes
      '_geom_hbond_distance_DA'        'H-bond D...A'     yes
      '_geom_hbond_angle_DHA'          'H-bond D-H...A'   yes

;
;
    Example 1 - directive to include a hydrogen-bonding table, including
                cosmetic headings in comments.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _publ_manuscript_incl_extra_item
    _publ_manuscript_incl_extra_info
    _publ_manuscript_incl_extra_defn
      '_atom_site_symmetry_multiplicity'
                         'to emphasise special sites'      yes
      '_chemical_compound_source'
                         'rare material, unusual source'   yes
      '_reflns_d_resolution_high'
                         'limited data is a problem here'  yes
      '_crystal_magnetic_permeability'
                         'unusual value for this material'  no
;
;
    Example 2 - hypothetical example including both standard CIF data items
                and a non-CIF quantity which the author wishes to list.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the PUBL_MANUSCRIPT_INCL category allow
               the authors of a manuscript submitted for publication to list
               data names that should be added to the standard request list
               used by the journal printing software. Although these fields are
               primarily intended to identify CIF data items that the author
               wishes to include in a published paper, they can also be used
               to identify data names created so that non-CIF items can be
               included in the publication. Note that *_item names MUST be
               enclosed in single quotes.
;

data_publ_manuscript_incl_extra_defn
    _name                      '_publ_manuscript_incl_extra_defn'
    _category                    publ_manuscript_incl
    _type                        char
    _list                        yes
    _list_reference            '_publ_manuscript_incl_extra_item'
    loop_ _enumeration
          _enumeration_detail
                                 no  'not a standard CIF data name'
                                 n   'abbreviation for "no"'
                                 yes 'a standard CIF data name'
                                 y   'abbreviation for "yes"'
    _enumeration_default         yes
    _definition
;              Flags whether the corresponding data item marked for inclusion
               in a journal request list is a standard CIF definition or not.
;

data_publ_manuscript_incl_extra_info
    _name                      '_publ_manuscript_incl_extra_info'
    _category                    publ_manuscript_incl
    _type                        char
    _list                        yes
    _list_reference            '_publ_manuscript_incl_extra_item'
    _definition
;              A short note indicating the reason why the author wishes the
               corresponding data item marked for inclusion in the journal
               request list to be published.
;

data_publ_manuscript_incl_extra_item
    _name                      '_publ_manuscript_incl_extra_item'
    _category                    publ_manuscript_incl
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _definition
;              Specifies the inclusion of specific data into a manuscript
               which are not normally requested by the journal. The values
               of this item are the extra data names (which MUST be enclosed
               in single quotes) that will be added to the journal request list.
;

############
## REFINE ##
############

data_refine_[]
    _name                      '_refine_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _refine_special_details     sfls:_F_calc_weight_full_matrix

    _refine_ls_structure_factor_coef   F
    _refine_ls_matrix_type             full
    _refine_ls_weighting_scheme        calc
    _refine_ls_weighting_details      'w=1/(u^2^(F)+0.0004F^2^)'
    _refine_ls_hydrogen_treatment      refxyz
    _refine_ls_extinction_method       Zachariasen
    _refine_ls_extinction_coef         3514(42)
    _refine_ls_extinction_expression
    ; Larson, A. C. (1970). "Crystallographic Computing", edited
      by F. R. Ahmed. Eq. (22) p. 292. Copenhagen: Munksgaard.
    ;
    _refine_ls_abs_structure_details
    ; The absolute configuration was assigned to agree with that
      of its precursor l-leucine at the chiral centre C3.
    ;
    _refine_ls_number_reflns           1408
    _refine_ls_number_parameters       272
    _refine_ls_number_restraints       0
    _refine_ls_number_constraints      0
    _refine_ls_R_factor_all            .038
    _refine_ls_R_factor_gt             .034
    _refine_ls_wR_factor_all           .044
    _refine_ls_wR_factor_gt            .042
    _refine_ls_goodness_of_fit_all    1.462
    _refine_ls_goodness_of_fit_gt     1.515
    _refine_ls_shift/su_max            .535
    _refine_ls_shift/su_mean           .044
    _refine_diff_density_min          -.108
    _refine_diff_density_max           .131
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the REFINE category record details about the
               structure-refinement parameters.
;

data_refine_diff_density_
    loop_ _name                '_refine_diff_density_max'
                               '_refine_diff_density_min'
                               '_refine_diff_density_rms'
    _category                    refine
    _type                        numb
    _type_conditions             esd
    _units                       e_A^-3^
    _units_detail              'electrons per cubic angstrom'
    _definition
;              The largest and smallest values and the root-mean-square
               deviation, in electrons per angstrom cubed, of the final
               difference electron density. The *_rms value is measured with
               respect to the arithmetic mean density and is derived from
               summations over each grid point in the asymmetric unit of
               the cell. This quantity is useful for assessing the
               significance of *_min and *_max values, and also for
               defining suitable contour levels.
;

data_refine_ls_abs_structure_details
    _name                      '_refine_ls_abs_structure_details'
    _category                    refine
    _type                        char
    _definition
;              The nature of the absolute structure and how it was determined.
;

data_refine_ls_abs_structure_Flack
    _name                      '_refine_ls_abs_structure_Flack'
    _category                    refine
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:1.0
    _definition
;              The measure of absolute structure as defined by Flack (1983).

               For centrosymmetric structures, the only permitted value, if the
               data name is present, is 'inapplicable', represented by '.' .

               For noncentrosymmetric structures, the value must lie in the
               99.97% Gaussian confidence interval  -3u =< x =< 1 + 3u and a
               standard uncertainty (e.s.d.) u must be supplied. The
               _enumeration_range of 0.0:1.0 is correctly interpreted as
               meaning (0.0 - 3u) =< x =< (1.0 + 3u).

               Ref: Flack, H. D. (1983). Acta Cryst. A39, 876-881.
;

data_refine_ls_abs_structure_Rogers
    _name                      '_refine_ls_abs_structure_Rogers'
    _category                    refine
    _type                        numb
    _type_conditions             esd
    _enumeration_range           -1.0:1.0
    _definition
;              The measure of absolute structure as defined by Rogers (1981).

               The value must lie in the 99.97% Gaussian confidence interval
               -1 -3u =< \h =< 1 + 3u and a standard uncertainty (e.s.d.) u must
               be supplied. The _enumeration_range of -1.0:1.0 is correctly
               interpreted as meaning (-1.0 - 3u) =< \h =< (1.0 + 3u).

               Ref: Rogers, D. (1981). Acta Cryst. A37, 734-741.
;

data_refine_ls_d_res_high
    _name                      '_refine_ls_d_res_high'
    _category                    refine
    _type                        numb
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The smallest value in angstroms of the interplanar spacings
               of the reflections used in the refinement. This is called
               the highest resolution.
;

data_refine_ls_d_res_low
    _name                      '_refine_ls_d_res_low'
    _category                    refine
    _type                        numb
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The largest value in angstroms of the interplanar spacings
               of the reflections used in the refinement. This is called
               the lowest resolution.
;

data_refine_ls_extinction_coef
    _name                      '_refine_ls_extinction_coef'
    _category                    refine
    _type                        numb
    _type_conditions             esd
    _example                     3472(52)
    _example_detail             'Zachariasen coefficient r* = 0.347(5) E04'
    _definition
;              The extinction coefficient used to calculate the correction
               factor applied to the structure-factor data. The nature of the
               extinction coefficient is given in the definitions of
               _refine_ls_extinction_expression and
               _refine_ls_extinction_method.

               For the 'Zachariasen' method it is the r* value; for the
               'Becker-Coppens type 1 isotropic' method it is the 'g' value
               and for 'Becker-Coppens type 2 isotropic' corrections it is
               the 'rho' value. Note that the magnitude of these values is
               usually of the order of 10000.

               Ref:  Becker, P. J. & Coppens, P. (1974). Acta Cryst. A30,
                     129-147, 148-153.
                     Zachariasen, W. H. (1967). Acta Cryst. 23, 558-564.
                     Larson, A. C. (1967). Acta Cryst. 23, 664-665.
;

data_refine_ls_extinction_expression
    _name                      '_refine_ls_extinction_expression'
    _category                    refine
    _type                        char
    _example
;                            Larson, A. C. (1970). "Crystallographic Computing",
                             edited by F. R. Ahmed. Eq. (22), p. 292.
                             Copenhagen: Munksgaard.
;
    _definition
;              A description of or reference to the extinction-correction
               equation used to apply the data item _refine_ls_extinction_coef.
               This information must be sufficient to reproduce the
               extinction-correction factors applied to the structure factors.
;

data_refine_ls_extinction_method
    _name                      '_refine_ls_extinction_method'
    _category                    refine
    _type                        char
    _enumeration_default        'Zachariasen'
    loop_ _example              'B-C type 2 Gaussian isotropic'
                                'none'
    _definition
;              A description of the extinction-correction method applied.
               This description should
               include information about the correction method, either
               'Becker-Coppens' or 'Zachariasen'. The latter is sometimes
               referred to as the 'Larson' method even though it employs
               Zachariasen's formula.

               The Becker-Coppens procedure is referred to as 'type 1' when
               correcting secondary extinction dominated by the mosaic spread;
               as 'type 2' when secondary extinction is dominated by particle
               size and includes a primary extinction component; and as 'mixed'
               when there is a mixture of types 1 and 2.

               For the Becker-Coppens method, it is also necessary to set the
               mosaic distribution as either 'Gaussian' or 'Lorentzian' and
               the nature of the extinction as 'isotropic' or 'anisotropic'.
               Note that if either the 'mixed' or 'anisotropic' corrections
               are applied, the multiple coefficients cannot be contained in
               *_extinction_coef and must be listed in _refine_special_details.

               Ref:  Becker, P. J. & Coppens, P. (1974). Acta Cryst. A30,
                     129-147, 148-153.
                     Zachariasen, W. H. (1967). Acta Cryst. 23, 558-564.
                     Larson, A. C. (1967). Acta Cryst. 23, 664-665.
;

data_refine_ls_F_calc_details
    _name                      '_refine_ls_F_calc_details'
    _category                    refine
    _type                        char
    loop_ _example               'Gaussian integration using 16 points'
;                                Bessel functions expansion up to 5th order.
                                 Bessel functions estimated accuracy: better
                                 than 0.001 electrons.
;
    _definition
;              Details concerning the evaluation of the structure
               factors using the expression given in
               _refine_ls_F_calc_formula.
;

data_refine_ls_F_calc_formula
    _name                      '_refine_ls_F_calc_formula'
    _category                    refine
    _type                        char
    _definition
;              Analytical expression used to calculate the structure factors.  
;

data_refine_ls_F_calc_precision
    _name                      '_refine_ls_F_calc_precision'
    _category                    refine
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              This item gives an estimate of the precision resulting
               from the numerical approximations made during the evaluation
               of the structure factors using the expression given in
               _refine_ls_F_calc_formula following the method outlined
               in _refine_ls_F_calc_details.  For X-ray diffraction the
               result is given in electrons.
;

data_refine_ls_goodness_of_fit_all
    _name                      '_refine_ls_goodness_of_fit_all'
    _category                    refine
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _definition
;              The least-squares goodness-of-fit parameter S for all
               reflections after the final cycle of refinement.
               Ideally, account should be taken of parameters restrained
               in the least-squares refinement. See also
               _refine_ls_restrained_S_ definitions.

                   {  sum { w [ Y(obs) - Y(calc) ]^2^ }  }^1/2^
               S = { ----------------------------------- }
                   {            Nref - Nparam            }

               Y(obs)  = the observed coefficients
                         (see _refine_ls_structure_factor_coef)
               Y(calc) = the calculated coefficients
                         (see _refine_ls_structure_factor_coef)
               w       = the least-squares reflection weight
                         [1/(u^2^)]
               u       = the standard uncertainty

               Nref   = the number of reflections used in the refinement
               Nparam = the number of refined parameters

               and the sum is taken over the specified reflections
;

data_refine_ls_goodness_of_fit_gt
    _name                      '_refine_ls_goodness_of_fit_gt'
    _category                    refine
    _type                        numb
    _type_conditions             esd
    _related_item              '_refine_ls_goodness_of_fit_obs'
    _related_function            alternate
    _enumeration_range           0.0:
    _definition
;              The least-squares goodness-of-fit parameter S for
               significantly intense reflections (see
               _reflns_threshold_expression) after the final cycle of
               refinement. Ideally, account should be taken of parameters
               restrained in the least-squares refinement. See also
               _refine_ls_restrained_S_ definitions.

                   {  sum { w [ Y(obs) - Y(calc) ]^2^ }  }^1/2^
               S = { ----------------------------------- }
                   {            Nref - Nparam            }

               Y(obs)  = the observed coefficients
                         (see _refine_ls_structure_factor_coef)
               Y(calc) = the calculated coefficients
                         (see _refine_ls_structure_factor_coef)
               w       = the least-squares reflection weight
                         [1/(u^2^)]
               u       = standard uncertainty

               Nref   = the number of reflections used in the refinement
               Nparam = the number of refined parameters

               and the sum is taken over the specified reflections
;

data_refine_ls_goodness_of_fit_obs
    _name                      '_refine_ls_goodness_of_fit_obs'
    _category                    refine
    _type                        numb
    _type_conditions             esd
    _related_item              '_refine_ls_goodness_of_fit_gt'
    _related_function            replace
    _enumeration_range           0.0:
    _definition
;              The least-squares goodness-of-fit parameter S for observed
               reflections (see _reflns_observed_criterion) after the final
               cycle of refinement. Ideally, account should be taken of
               parameters restrained in the least-squares refinement. See also
               _refine_ls_restrained_S_ definitions.

                   {  sum { w [ Y(obs) - Y(calc) ]^2^ }  }^1/2^
               S = { ----------------------------------- }
                   {            Nref - Nparam            }

               Y(obs)  = the observed coefficients
                         (see _refine_ls_structure_factor_coef)
               Y(calc) = the calculated coefficients
                         (see _refine_ls_structure_factor_coef)
               w       = the least-squares reflection weight
                         [1/(u^2^)]
               u       = standard uncertainty (e.s.d.)

               Nref   = the number of reflections used in the refinement
               Nparam = the number of refined parameters

               and the sum is taken over the specified reflections
;

data_refine_ls_goodness_of_fit_ref
    _name                      '_refine_ls_goodness_of_fit_ref'
    _category                    refine
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _definition
;              The least-squares goodness-of-fit parameter S for all
               reflections included in the refinement after the final cycle
               of refinement. Ideally, account should be taken of parameters
               restrained in the least-squares refinement. See also
               _refine_ls_restrained_S_ definitions.

                   {  sum | w | Y(obs) - Y(calc) |^2^ |  }^1/2^
               S = { ----------------------------------- }
                   {            Nref - Nparam            }

               Y(obs)  = the observed coefficients
                         (see _refine_ls_structure_factor_coef)
               Y(calc) = the calculated coefficients
                         (see _refine_ls_structure_factor_coef)
               w       = the least-squares reflection weight
                         [1/(u^2^)]
               u       = standard uncertainty

               Nref   = the number of reflections used in the refinement
               Nparam = the number of refined parameters

               and the sum is taken over the specified reflections
;

data_refine_ls_hydrogen_treatment
    _name                      '_refine_ls_hydrogen_treatment'
    _category                    refine
    _type                        char
    loop_ _enumeration
          _enumeration_detail    refall  'refined all H-atom parameters'
                                 refxyz  'refined H-atom coordinates only'
                                 refU    'refined H-atom U's only'
                                 noref   'no refinement of H-atom parameters'
                                 constr  'H-atom parameters constrained'
                                 mixed   'some constrained, some independent'
                                 undef   'H-atom parameters not defined'
    _enumeration_default         undef
    _definition
;              Treatment of hydrogen atoms in the least-squares refinement.
;

data_refine_ls_matrix_type
    _name                      '_refine_ls_matrix_type'
    _category                    refine
    _type                        char
    loop_ _enumeration
          _enumeration_detail    full       'full'
                                 fullcycle  'full with fixed elements per cycle'
                                 atomblock  'block diagonal per atom'
                                 userblock  'user-defined blocks'
                                 diagonal   'diagonal elements only'
                                 sparse     'selected elements only'
    _enumeration_default         full
    _definition
;              Type of matrix used to accumulate the least-squares derivatives.
;

data_refine_ls_number_constraints
    _name                      '_refine_ls_number_constraints'
    _category                    refine
    _type                        numb
    _enumeration_range           0:
    _enumeration_default         0
    _definition
;              The number of constrained (non-refined or dependent) parameters
               in the least-squares process. These may be due to symmetry or any
               other constraint process (e.g. rigid-body refinement). See also
               _atom_site_constraints and _atom_site_refinement_flags. A general
               description of constraints may appear in _refine_special_details.
;

data_refine_ls_number_parameters
    _name                      '_refine_ls_number_parameters'
    _category                    refine
    _type                        numb
    _enumeration_range           0:
    _definition
;              The number of parameters refined in the least-squares process.
               If possible, this number should include some contribution from
               the restrained parameters. The restrained parameters are
               distinct from the constrained parameters (where one or more
               parameters are linearly dependent on the refined value of
               another). Least-squares restraints often depend on geometry or
               energy considerations and this makes their direct contribution
               to this number, and to the goodness-of-fit calculation,
               difficult to assess.
;

data_refine_ls_number_reflns
    _name                      '_refine_ls_number_reflns'
    _category                    refine
    _type                        numb
    _enumeration_range           0:
    _definition
;              The number of unique reflections contributing to the
               least-squares refinement calculation.
;

data_refine_ls_number_restraints
    _name                      '_refine_ls_number_restraints'
    _category                    refine
    _type                        numb
    _enumeration_range           0:
    _definition
;              The number of restrained parameters. These are parameters which
               are not directly dependent on another refined parameter.
               Restrained parameters often involve geometry or energy
               dependencies.
               See also _atom_site_constraints and _atom_site_refinement_flags.
               A general description of refinement constraints may appear in
               _refine_special_details.
;

data_refine_ls_R_factor_all
    _name                      '_refine_ls_R_factor_all'
    _category                    refine
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              Residual factor for all reflections satisfying the
               resolution limits established by _refine_ls_d_res_high and
               _refine_ls_d_res_low. This is the conventional R
               factor. See also _refine_ls_wR_factor_ definitions.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the specified reflections
;

data_refine_ls_R_factor_gt
    _name                      '_refine_ls_R_factor_gt'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_R_factor_obs'
    _related_function            alternate
    _enumeration_range           0.0:
    _definition
;              Residual factor for the reflections (with number given by
               _reflns_number_gt) judged significantly intense (i.e. satisfying
               the threshold specified by _reflns_threshold_expression)
               and included in the refinement. The reflections also satisfy
               the resolution limits established by _refine_ls_d_res_high and
               _refine_ls_d_res_low. This is the conventional R
               factor. See also _refine_ls_wR_factor_ definitions.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the specified reflections
;

data_refine_ls_R_factor_obs
    _name                      '_refine_ls_R_factor_obs'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_R_factor_gt'
    _related_function            replace
    _enumeration_range           0.0:
    _definition
;              Residual factor for the reflections classified as 'observed'
               (see _reflns_observed_criterion) and included in the
               refinement. The reflections also satisfy the resolution limits
               established by _refine_ls_d_res_high and
               _refine_ls_d_res_low. This is the conventional R
               factor. See also _refine_ls_wR_factor_ definitions.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the specified reflections
;

data_refine_ls_R_Fsqd_factor
    _name                       '_refine_ls_R_Fsqd_factor'
    _category                    refine
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              Residual factor R(Fsqd), calculated on the squared amplitudes
               of the observed and calculated structure factors, for
               significantly intense reflections (satisfying
               _reflns_threshold_expression) and included in the refinement.

               The reflections also satisfy the resolution limits established
               by _refine_ls_d_res_high and _refine_ls_d_res_low.

                          sum | F(obs)^2^ - F(calc)^2^ |
               R(Fsqd) = -------------------------------
                                  sum F(obs)^2^

               F(obs)^2^  = squares of the observed structure-factor amplitudes
               F(calc)^2^ = squares of the calculated structure-factor
                            amplitudes

               and the sum is taken over the specified reflections
;

data_refine_ls_R_I_factor
    _name                       '_refine_ls_R_I_factor'
    _category                    refine
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              Residual factor R(I) for significantly intense reflections
               (satisfying _reflns_threshold_expression) and included in
               the refinement.

               This is most often calculated in Rietveld refinements against
               powder data, where it is referred to as R~B~ or R~Bragg~.

                       sum | I(obs) - I(calc) |
               R(I) =  ------------------------
                              sum | I(obs) |

               I(obs)  = the net observed intensities
               I(calc) = the net calculated intensities

               and the sum is taken over the specified reflections
;

data_refine_ls_restrained_S_all
    _name                      '_refine_ls_restrained_S_all'
    _category                    refine
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              The least-squares goodness-of-fit parameter S' for all
               reflections after the final cycle of least-squares refinement.
               This parameter explicitly includes the restraints applied in the
               least-squares process. See also _refine_ls_goodness_of_fit_
               definitions.

                    {sum { w [ Y(obs) - Y(calc) ]^2^ }                   }^1/2^
                    {         + sum~r~ { w~r~ [ P(calc) - P(targ) ]^2^ } }
               S' = { -------------------------------------------------- }
                    {            N~ref~ + N~restr~ - N~param~            }

               Y(obs)   = the observed coefficients
                          (see _refine_ls_structure_factor_coef)
               Y(calc)  = the calculated coefficients
                          (see _refine_ls_structure_factor_coef)
               w        = the least-squares reflection weight
                          [1/square of standard uncertainty (e.s.d.)]

               P(calc)  = the calculated restraint values
               P(targ)  = the target restraint values
               w~r~     = the restraint weight

               N~ref~   = the number of reflections used in the refinement
                        (see _refine_ls_number_reflns)
               N~restr~ = the number of restraints
                        (see _refine_ls_number_restraints)
               N~param~ = the number of refined parameters
                        (see _refine_ls_number_parameters)

               sum     is taken over the specified reflections
               sum~r~  is taken over the restraints
;

data_refine_ls_restrained_S_gt
    _name                      '_refine_ls_restrained_S_gt'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_restrained_S_obs'
    _related_function            alternate
    _enumeration_range           0.0:
    _definition
;              The least-squares goodness-of-fit parameter S' for
               significantly intense reflections (satisfying
               _reflns_threshold_expression) after the final cycle
               of least-squares refinement. This parameter explicitly includes
               the restraints applied in the least-squares process.
               See also _refine_ls_goodness_of_fit_ definitions.

                    {sum { w [ Y(obs) - Y(calc) ]^2^ }                   }^1/2^
                    {         + sum~r~ { w~r~ [ P(calc) - P(targ) ]^2^ } }
               S' = { -------------------------------------------------- }
                    {            N~ref~ + N~restr~ - N~param~            }

               Y(obs)   = the observed coefficients
                          (see _refine_ls_structure_factor_coef)
               Y(calc)  = the calculated coefficients
                          (see _refine_ls_structure_factor_coef)
               w        = the least-squares reflection weight
                          [1/square of standard uncertainty (e.s.d.)]

               P(calc)  = the calculated restraint values
               P(targ)  = the target restraint values
               w~r~     = the restraint weight

               N~ref~   = the number of reflections used in the refinement
                        (see _refine_ls_number_reflns)
               N~restr~ = the number of restraints
                        (see _refine_ls_number_restraints)
               N~param~ = the number of refined parameters
                        (see _refine_ls_number_parameters)

               sum     is taken over the specified reflections
               sum~r~  is taken over the restraints
;

data_refine_ls_restrained_S_obs
    _name                      '_refine_ls_restrained_S_obs'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_restrained_S_gt'
    _related_function            replace
    _enumeration_range           0.0:
    _definition
;              The least-squares goodness-of-fit parameter S' for observed
               reflections after the final cycle of least-squares refinement.
               This parameter explicitly includes the restraints applied in the
               least-squares process.  See also _refine_ls_goodness_of_fit_
               definitions.

                    {sum { w [ Y(obs) - Y(calc) ]^2^ }                   }^1/2^
                    {         + sum~r~ { w~r~ [ P(calc) - P(targ) ]^2^ } }
               S' = { -------------------------------------------------- }
                    {            N~ref~ + N~restr~ - N~param~            }

               Y(obs)   = the observed coefficients
                          (see _refine_ls_structure_factor_coef)
               Y(calc)  = the calculated coefficients
                          (see _refine_ls_structure_factor_coef)
               w        = the least-squares reflection weight
                          [1/square of standard uncertainty (e.s.d.)]

               P(calc)  = the calculated restraint values
               P(targ)  = the target restraint values
               w~r~     = the restraint weight

               N~ref~   = the number of reflections used in the refinement
                        (see _refine_ls_number_reflns)
               N~restr~ = the number of restraints
                        (see _refine_ls_number_restraints)
               N~param~ = the number of refined parameters
                        (see _refine_ls_number_parameters)

               sum     is taken over the specified reflections
               sum~r~  is taken over the restraints
;

data_refine_ls_shift/esd_max
    _name                      '_refine_ls_shift/esd_max'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_shift/su_max'
    _related_function            replace
    _enumeration_range           0.0:
    _definition
;              The largest ratio of the final least-squares parameter
               shift to the final standard uncertainty (s.u.,
               formerly described as estimated standard deviation, e.s.d.).
;

data_refine_ls_shift/esd_mean
    _name                      '_refine_ls_shift/esd_mean'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_shift/su_mean'
    _related_function            replace
    _enumeration_range           0.0:
    _definition
;              The average ratio of the final least-squares parameter
               shift to the final standard uncertainty (s.u.,
               formerly described as estimated standard deviation, e.s.d.).
;

data_refine_ls_shift/su_max
    _name                      '_refine_ls_shift/su_max'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_shift/esd_max'
    _related_function            alternate
    _enumeration_range           0.0:
    _definition
;              The largest ratio of the final least-squares parameter
               shift to the final standard uncertainty.
;

data_refine_ls_shift/su_max_lt
    _name                      '_refine_ls_shift/su_max_lt'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_shift/su_max'
    _related_function            alternate
    _enumeration_range           0.0:
    _definition
;              An upper limit for the largest ratio of the final
               least-squares parameter shift to the final
               standard uncertainty.  This item is used when the largest
               value of the shift divided by the final standard uncertainty
               is too small to measure.
;

data_refine_ls_shift/su_mean
    _name                      '_refine_ls_shift/su_mean'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_shift/esd_mean'
    _related_function            alternate
    _enumeration_range           0.0:
    _definition
;              The average ratio of the final least-squares parameter
               shift to the final standard uncertainty.
;

data_refine_ls_shift/su_mean_lt
    _name                      '_refine_ls_shift/su_mean_lt'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_shift/su_mean'
    _related_function            alternate
    _enumeration_range           0.0:
    _definition
;              An upper limit for the average ratio of the final
               least-squares parameter shift to the
               final standard uncertainty.  This
               item is used when the average value of the shift divided by
               the final standard uncertainty is too small to measure.
;

data_refine_ls_structure_factor_coef
    _name                      '_refine_ls_structure_factor_coef'
    _category                    refine
    _type                        char
    loop_ _enumeration
          _enumeration_detail    F      'structure-factor magnitude'
                                 Fsqd   'structure factor squared'
                                 Inet   'net intensity'
    _enumeration_default         F
    _definition
;              Structure-factor coefficient |F|, F^2^ or I used in the
               least-squares refinement process.
;

data_refine_ls_weighting_details

    _name                      '_refine_ls_weighting_details'
    _category                    refine
    _type                        char
    _example
;                  Sigdel model of Konnert-Hendrickson:
                   Sigdel = Afsig +  Bfsig*(sin(\q)/\l - 1/6)
                   Afsig = 22.0, Bfsig = 150.0 at the beginning of refinement.
                   Afsig = 16.0, Bfsig =  60.0 at the end of refinement.
;
    _definition
;              A description of special aspects of the weighting scheme used
               in the least-squares refinement. Used to describe the weighting
               when the value of _refine_ls_weighting_scheme is specified
               as 'calc'.
;

data_refine_ls_weighting_scheme
    _name                      '_refine_ls_weighting_scheme'
    _category                    refine
    _type                        char
    loop_ _enumeration
          _enumeration_detail    sigma    "based on measured s.u.'s"
                                 unit     'unit or no weights applied'
                                 calc     'calculated weights applied'
    _enumeration_default         sigma
    _definition
;              The weighting scheme applied in the least-squares process. The
               standard code may be followed by a description of the weight
               (but see _refine_ls_weighting_details for a preferred approach).
;

data_refine_ls_wR_factor_all
    _name                      '_refine_ls_wR_factor_all'
    _category                    refine
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              Weighted residual factors for all reflections.
               The reflections also satisfy the resolution limits established
               by _refine_ls_d_res_high and _refine_ls_d_res_low.
               See also the _refine_ls_R_factor_ definitions.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitude specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitude specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weight

               and the sum is taken over the specified reflections
;

data_refine_ls_wR_factor_gt
    _name                      '_refine_ls_wR_factor_gt'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_wR_factor_obs'
    _related_function            alternate
    _enumeration_range           0.0:
    _definition
;              Weighted residual factors for significantly intense reflections
               (satisfying _reflns_threshold_expression) included in the
               refinement.  The reflections also satisfy the resolution
               limits established by _refine_ls_d_res_high and
               _refine_ls_d_res_low.  See also the _refine_ls_R_factor_
               definitions.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitude specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitude specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weight

               and the sum is taken over the specified reflections
;

data_refine_ls_wR_factor_obs
    _name                      '_refine_ls_wR_factor_obs'
    _category                    refine
    _type                        numb
    _related_item              '_refine_ls_wR_factor_gt'
    _related_function            replace
    _enumeration_range           0.0:
    _definition
;              Weighted residual factors for the reflections classified as
               'observed' (see _reflns_observed_criterion) and included
               in the refinement.  The reflections also satisfy the resolution
               limits established by _refine_ls_d_res_high and
               _refine_ls_d_res_low. See also the _refine_ls_R_factor_
               definitions.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitude specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitude specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weight

               and the sum is taken over the specified reflections
;

data_refine_ls_wR_factor_ref
    _name                      '_refine_ls_wR_factor_ref'
    _category                    refine
    _type                        numb
    _enumeration_range           0.0:
    _definition
;              Weighted residual factors for all reflections included in the
               refinement.  The reflections also satisfy the resolution
               limits established by _refine_ls_d_res_high and
               _refine_ls_d_res_low.  See also the _refine_ls_R_factor_
               definitions.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitude specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitude specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weight

               and the sum is taken over the specified reflections
;

data_refine_special_details
    _name                      '_refine_special_details'
    _category                    refine
    _type                        char
    _definition
;              Description of special aspects of the refinement process.
;

#####################
## REFINE_LS_CLASS ##
#####################

data_refine_ls_class_[]
    _name                      '_refine_ls_class_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
        _refine_ls_class_R_factor_gt
        _refine_ls_class_code
                0.057    'Main'
                0.074    'Com'
                0.064    'NbRefls'
                0.046    'LaRefls'
                0.112    'Sat1'
                0.177    'Sat2'
;
;
    Example 1 - example for a modulated structure extracted from van Smaalen
                [J. Phys. Condens. Matter (1991), 3, 1247-1263.]
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      _definition
;              Data items in the REFINE_LS_CLASS category record details
               (for each reflection class separately) about the reflections
               used for the structure refinement.
;

data_refine_ls_class_code
    _name                      '_refine_ls_class_code'
    _category                    refine_ls_class
    _type                        char
    _list                        yes
    _list_link_parent          '_reflns_class_code'
    loop_ _example               '1'
                                 'm1'
                                 's2'
    _definition
;              The code identifying a certain reflection class. This code must
               match a _reflns_class_code.
;

data_refine_ls_class_d_res_high
    _name                      '_refine_ls_class_d_res_high'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              For each reflection class, the highest resolution in angstroms
               for the reflections used in the refinement. This is
               the lowest d value in a reflection class.
;

data_refine_ls_class_d_res_low
    _name                      '_refine_ls_class_d_res_low'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              For each reflection class, the lowest resolution in angstroms
               for the reflections used in the refinement. This is
               the highest d value in a reflection class.
;

data_refine_ls_class_R_factor_
    loop_ _name                '_refine_ls_class_R_factor_all'
                               '_refine_ls_class_R_factor_gt'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factors for all
               reflections, and for significantly intense reflections (see
               _reflns_threshold_expression), included in the refinement.
               The reflections also satisfy the resolution limits established by
               _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.
               This is the conventional R factor.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the reflections of this class. See also
               _refine_ls_class_wR_factor_all definitions.
;

data_refine_ls_class_R_Fsqd_factor
    _name                      '_refine_ls_class_R_Fsqd_factor'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factor R(F^2^) calculated
               on the squared amplitudes of the observed and calculated
               structure factors for the reflections judged significantly
               intense (i.e. satisfying the threshold specified by
               _reflns_threshold_expression) and included in the refinement.

               The reflections also satisfy the resolution limits established
               by _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.

                          sum | F(obs)^2^ - F(calc)^2^ |
               R(Fsqd) = -------------------------------
                                  sum F(obs)^2^

               F(obs)^2^  = squares of the observed structure-factor amplitudes
               F(calc)^2^ = squares of the calculated structure-factor
                            amplitudes

               and the sum is taken over the reflections of this class.
;

data_refine_ls_class_R_I_factor
    _name                      '_refine_ls_class_R_I_factor'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factor R(I) for the
               reflections judged significantly intense (i.e. satisfying the
               threshold specified by _reflns_threshold_expression) and
               included in the refinement.

               This is most often calculated in Rietveld refinements
               against powder data, where it is referred to as R~B~ or R~Bragg~.

                       sum | I(obs) - I(calc) |
               R(I) =  ------------------------
                              sum | I(obs) |

               I(obs)  = the net observed intensities
               I(calc) = the net calculated intensities

               and the sum is taken over the reflections of this class.
;

data_refine_ls_class_wR_factor_all
    _name                      '_refine_ls_class_wR_factor_all'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference            '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the weighted residual factors for all
               reflections included in the refinement. The reflections also
               satisfy the resolution limits established by
               _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitudes specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitudes specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weights

               and the sum is taken over the reflections of this class. See
               also _refine_ls_class_R_factor_ definitions.
;

###########
## REFLN ##
###########

data_refln_[]
    _name                      '_refln_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
     _refln_index_h
     _refln_index_k
     _refln_index_l
     _refln_F_squared_calc
     _refln_F_squared_meas
     _refln_F_squared_sigma
     _refln_include_status
       2   0   0       85.57       58.90      1.45 o
       3   0   0    15718.18    15631.06     30.40 o
       4   0   0    55613.11    49840.09     61.86 o
       5   0   0      246.85      241.86     10.02 o
       6   0   0       82.16       69.97      1.93 o
       7   0   0     1133.62      947.79     11.78 o
       8   0   0     2558.04     2453.33     20.44 o
       9   0   0      283.88      393.66      7.79 o
       10  0   0      283.70      171.98      4.26 o
;
;
    Example 1 - based on data set fetod of Todres, Yanovsky, Ermekov & Struchkov
                [Acta Cryst. (1993), C49, 1352-1354].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _refln_index_h
    _refln_index_k
    _refln_index_l
    _refln_F_meas
    _refln_F_calc
    _refln_F_sigma
    _refln_include_status
    _refln_scale_group_code
        0   0   6  34.935  36.034   3.143  o  1
        0   0  12  42.599  40.855   2.131  o  1
        0   1   0  42.500  42.507   4.719  o  1
        0   1   1  59.172  57.976   4.719  o  1
        0   1   2  89.694  94.741   4.325  o  1
        0   1   3  51.743  52.241   3.850  o  1
        0   1   4   9.294  10.318   2.346  o  1
        0   1   5  41.160  39.951   3.313  o  1
        0   1   6   6.755   7.102    .895  <  1
        0   1   7  30.693  31.171   2.668  o  1
        0   1   8  12.324  12.085   2.391  o  1
        0   1   9  15.348  15.122   2.239  o  1
        0   1  10  17.622  19.605   1.997  o  1
;
;
    Example 2 - based on standard test data set p6122 of the Xtal distribution
                [Hall, King & Stewart (1995). Xtal3.4 User's Manual. University
                of Western Australia].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the REFLN category record details about the
               reflections used to determine the ATOM_SITE data items.

               The REFLN data items refer to individual reflections and must
               be included in looped lists.

               The REFLNS data items specify the parameters that apply to all
               reflections. The REFLNS data items are not looped.
;

data_refln_A_
    loop_ _name                '_refln_A_calc'
                               '_refln_A_meas'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _definition
;              The calculated and measured structure-factor component A
               (in electrons for X-ray diffraction).

               A =|F|cos(phase)
;

data_refln_B_
    loop_ _name                '_refln_B_calc'
                               '_refln_B_meas'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _definition
;              The calculated and measured structure-factor component B
               (in electrons for X-ray diffraction).

               B =|F|sin(phase)
;

data_refln_class_code
    _name                      '_refln_class_code'
    _category                    refln
    _type                        char
    _list                        yes
    _list_reference            '_refln_index_'
    _list_link_parent          '_reflns_class_code'
    _definition
;              The code identifying the class to which this reflection has been
               assigned. This code must match a value of _reflns_class_code.
               Reflections may be grouped into classes for a variety of
               purposes. For example, for modulated structures each reflection
               class may be defined by the number m=sum|m~i~|, where the m~i~
               are the integer coefficients that, in addition to h,k,l, index
               the corresponding diffraction vector in the basis defined
               for the reciprocal lattice.
;

data_refln_crystal_id
    _name                      '_refln_crystal_id'
    _category                    refln
    _type                        char
    _list                        yes
    _list_link_parent          '_exptl_crystal_id'
    _list_reference            '_refln_index_'
    _definition
;              Code identifying each crystal if multiple crystals are used. Is
               used to link with _exptl_crystal_id in the _exptl_crystal_ list.
;

data_refln_d_spacing
    _name                      '_refln_d_spacing'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The d spacing in angstroms for this reflection. This is related
               to the (sin theta)/lambda value by the expression
                    _refln_d_spacing = 2/(_refln_sint/lambda)
;

data_refln_F_
    loop_ _name                '_refln_F_calc'
                               '_refln_F_meas'
                               '_refln_F_sigma'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _definition
;              The calculated, measured and standard uncertainty (derived from
               measurement) of the structure factors (in electrons for
               X-ray diffraction).
;

data_refln_F_squared_
    loop_ _name                '_refln_F_squared_calc'
                               '_refln_F_squared_meas'
                               '_refln_F_squared_sigma'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _definition
;              Calculated, measured and estimated standard uncertainty (derived
               from measurement) of the squared structure factors (in electrons
               squared for X-ray diffraction).
;

data_refln_include_status
    _name                      '_refln_include_status'
    _category                    refln
    _type                        char
    _related_item              '_refln_observed_status'
    _related_function            alternate
    _list                        yes
    _list_reference            '_refln_index_'
    loop_ _enumeration
          _enumeration_detail    o
;                                     (lower-case letter o for 'observed')
                                      satisfies _refine_ls_d_res_high
                                      satisfies _refine_ls_d_res_low
                                      exceeds _reflns_threshold_expression
;
                                 <
;                                     satisfies _refine_ls_d_res_high
                                      satisfies _refine_ls_d_res_low
                                      does not exceed
                                        _reflns_threshold_expression
;
                                 -  'systematically absent reflection'
                                 x  'unreliable measurement -- not used'
                                 h  'does not satisfy _refine_ls_d_res_high'
                                 l  'does not satisfy _refine_ls_d_res_low'
    _enumeration_default         o
    _definition
;              Classification of a reflection indicating its status with
               respect to inclusion in the refinement and the calculation
               of R factors.
;

data_refln_index_
    loop_ _name                '_refln_index_h'
                               '_refln_index_k'
                               '_refln_index_l'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_mandatory              yes
    _definition
;              Miller indices of the reflection. The values of the Miller
               indices in the REFLN category must correspond to the cell
               defined by the cell lengths and cell angles in the CELL category.
;

data_refln_intensity_
    loop_ _name                '_refln_intensity_calc'
                               '_refln_intensity_meas'
                               '_refln_intensity_sigma'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _definition
;              The calculated, measured and standard uncertainty (derived from
               measurement) of the intensity, all in the same arbitrary units
               as _refln_intensity_meas.
;

data_refln_mean_path_length_tbar
    _name                      '_refln_mean_path_length_tbar'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _enumeration_range           0.0:
    _units                       mm
    _units_detail              'millimetres'
    _definition
;              Mean path length in millimetres through the crystal for this
               reflection.
;

data_refln_observed_status
    _name                      '_refln_observed_status'
    _category                    refln
    _type                        char
    _related_item              '_refln_include_status'
    _related_function            replace
    _list                        yes
    _list_reference            '_refln_index_'
    loop_ _enumeration
          _enumeration_detail    o
;                                     satisfies _refine_ls_d_res_high
                                      satisfies _refine_ls_d_res_low
                                      observed by _reflns_observed_criterion
;
                                 <
;                                     satisfies _refine_ls_d_res_high
                                      satisfies _refine_ls_d_res_low
                                      unobserved by _reflns_observed_criterion
;
                                 -  'systematically absent reflection'
                                 x  'unreliable measurement -- not used'
                                 h  'does not satisfy _refine_ls_d_res_high'
                                 l  'does not satisfy _refine_ls_d_res_low'
    _enumeration_default         o
    _definition
;              Classification of a reflection indicating its status with
               respect to inclusion in the refinement and the calculation
               of R factors.
;

data_refln_phase_calc
    _name                      '_refln_phase_calc'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _units                       deg
    _units_detail              'degrees'
    _definition
;              The calculated structure-factor phase in degrees.
;

data_refln_phase_meas
    _name                      '_refln_phase_meas'
    _category                    refln
    _type                        numb
    _type_conditions             esd
    _list                        yes
    _list_reference            '_refln_index_'
    _units                       deg
    _units_detail              'degrees'
    _definition
;              The measured structure-factor phase in degrees.
;

data_refln_refinement_status
    _name                      '_refln_refinement_status'
    _category                    refln
    _type                        char
    _list                        yes
    _list_reference            '_refln_index_'
    loop_ _enumeration
          _enumeration_detail    incl    'included in ls process'
                                 excl    'excluded from ls process'
                                 extn    'excluded due to extinction'
    _enumeration_default         incl
    _definition
;              Status of a reflection in the structure-refinement process.
;

data_refln_refinement_status
    _name                      '_refln_refinement_status'
    _category                    refln
    _type                        char
    _list                        yes
    _list_reference            '_refln_index_'
    loop_ _enumeration
          _enumeration_detail    INCS    'included in ls process'
                                 EXCL    'excluded from ls process'
                                 EXTN    'excluded due to extinction'
    _enumeration_default         INCL
    _definition
;              Status of a reflection in the structure-refinement process.
;

data_refln_scale_group_code
    _name                      '_refln_scale_group_code'
    _category                    refln
    _type                        char
    _list                        yes
    _list_link_parent          '_reflns_scale_group_code'
    _list_reference            '_refln_index_'
    loop_ _example               1 2 3 s1 A B c1 c2 c3
    _definition
;              Code identifying the structure-factor scale. This code must
               correspond to one of the _reflns_scale_group_code values.
;

data_refln_sint/lambda
    _name                      '_refln_sint/lambda'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _enumeration_range           0.0:
    _units                       A^-1^
    _units_detail              'reciprocal angstroms'
    _definition
;              The (sin theta)/lambda value in reciprocal angstroms for this
               reflection.
;

data_refln_symmetry_epsilon
    _name                      '_refln_symmetry_epsilon'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _enumeration_range           1:48
    _definition
;              The symmetry reinforcement factor corresponding to the number of
               times the reflection indices are generated identically from the
               space-group symmetry operations.
;

data_refln_symmetry_multiplicity
    _name                      '_refln_symmetry_multiplicity'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _enumeration_range           1:48
    _definition
;              The number of reflections symmetry-equivalent under the Laue
               symmetry to the present reflection. In the Laue symmetry, Friedel
               opposites (h k l and -h -k -l) are equivalent. Tables of
               symmetry-equivalent reflections are available in International
               Tables for Crystallography Volume A (2002), Chapter 10.1.
;

data_refln_wavelength
    _name                      '_refln_wavelength'
    _category                    refln
    _type                        numb
    _list                        yes
    _list_reference            '_refln_index_'
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The mean wavelength in angstroms of the radiation used to measure
               this reflection. This is an important parameter for data
               collected using energy-dispersive detectors or the Laue method.
;

data_refln_wavelength_id
    _name                      '_refln_wavelength_id'
    _category                    refln
    _type                        char
    _list                        yes
    _list_link_parent          '_diffrn_radiation_wavelength_id'
    _list_reference            '_refln_index_'
    _definition
;              Code identifying the wavelength in the _diffrn_radiation_ list.
               See _diffrn_radiation_wavelength_id.
;

############
## REFLNS ##
############

data_reflns_[]
    _name                      '_reflns_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _reflns_limit_h_min                0
    _reflns_limit_h_max                6
    _reflns_limit_k_min                0
    _reflns_limit_k_max                17
    _reflns_limit_l_min                0
    _reflns_limit_l_max                22
    _reflns_number_total               1592
    _reflns_number_gt                  1408
    _reflns_threshold_expression       'F > 6.0u(F)'
    _reflns_d_resolution_high          0.8733
    _reflns_d_resolution_low           11.9202
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the REFLNS category record details about the
               reflections used to determine the ATOM_SITE data items.

               The REFLN data items refer to individual reflections and must
               be included in looped lists.

               The REFLNS data items specify the parameters that apply to all
               reflections. The REFLNS data items are not looped.
;

data_reflns_d_resolution_
    loop_ _name                '_reflns_d_resolution_high'
                               '_reflns_d_resolution_low'
    _category                    reflns
    _type                        numb
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The highest and lowest resolution in angstroms for the
               reflections. These are the smallest and largest d values.
;

data_reflns_Friedel_coverage
    _name                      '_reflns_Friedel_coverage'
    _category                    reflns
    _type                        numb
    _enumeration_range           0.0:1.0
    _definition
;              The proportion of Friedel-related reflections present in
               the number of 'independent' reflections specified by
               the item _reflns_number_total.

               This proportion is calculated as the ratio:

                 [N(crystal class) - N(Laue symmetry)] / N(Laue symmetry)

               where, working from the _diffrn_refln_ list,

               N(crystal class) is the number of reflections obtained on
                  averaging under the symmetry of the crystal class
               N(Laue symmetry) is the number of reflections obtained on
                  averaging under the Laue symmetry.

               Examples:
                 (a) For centrosymmetric structures, _reflns_Friedel_coverage
                     is necessarily equal to 0.0 as the crystal class
                     is identical to the Laue symmetry.
                 (b) For whole-sphere data for a crystal in the space
                     group P1, _reflns_Friedel_coverage is equal to 1.0,
                     as no reflection h k l is equivalent to -h -k -l
                     in the crystal class and all Friedel pairs
                     {h k l; -h -k -l} have been measured.
                 (c) For whole-sphere data in space group Pmm2,
                     _reflns_Friedel_coverage will be < 1.0 because
                     although reflections h k l and
                     -h -k -l are not equivalent when h k l indices are
                     nonzero, they are when l=0.
                 (d) For a crystal in the space group Pmm2, measurements of the
                     two inequivalent octants h >= 0, k >=0, l lead to the
                     same value as in (c), whereas measurements of the
                     two equivalent octants h >= 0, k, l >= 0 will lead to
                     a value of zero for _reflns_Friedel_coverage.
;

data_reflns_limit_
    loop_ _name                '_reflns_limit_h_max'
                               '_reflns_limit_h_min'
                               '_reflns_limit_k_max'
                               '_reflns_limit_k_min'
                               '_reflns_limit_l_max'
                               '_reflns_limit_l_min'
    _category                    reflns
    _type                        numb
    _definition
;              Miller indices limits for the reported reflections. These need
               not be the same as the _diffrn_reflns_limit_ values.
;

data_reflns_number_gt
    _name                      '_reflns_number_gt'
    _category                    reflns
    _type                        numb
    _related_item              '_reflns_number_observed'
    _related_function            alternate
    _enumeration_range           0:
    _definition
;              The number of reflections in the _refln_ list (not the
               _diffrn_refln_ list) that are significantly intense, satisfying
               the criterion specified by _reflns_threshold_expression. This may
               include Friedel-equivalent reflections (i.e. those which are
               symmetry-equivalent under the Laue symmetry but inequivalent
               under the crystal class) according to the nature of the
               structure and the procedures used. Special characteristics
               of the reflections included in the _refln_ list should be given
               in the item _reflns_special_details.
;

data_reflns_number_observed
    _name                      '_reflns_number_observed'
    _category                    reflns
    _type                        numb
    _related_item              '_reflns_number_gt'
    _related_function            replace
    _enumeration_range           0:
    _definition
;              The number of 'observed' reflections in the _refln_ list (not
               the _diffrn_refln_ list). The observed reflections satisfy the
               threshold criterion specified by _reflns_threshold_expression
               (or the deprecated item _reflns_observed_criterion). They may
               include Friedel-equivalent reflections according to the nature
               of the structure and the procedures used. Special characteristics
               of the reflections included in the _refln_ list should be given
               in the item _reflns_special_details.
;

data_reflns_number_total
    _name                      '_reflns_number_total'
    _category                    reflns
    _type                        numb
    _enumeration_range           0:
    _definition
;              The total number of reflections in the _refln_ list (not the
                _diffrn_refln_ list). This may include Friedel-equivalent
               reflections (i.e. those which are symmetry-equivalent under the
               Laue symmetry but inequivalent under the crystal class)
               according to the nature of the structure and the procedures
               used. Special characteristics of the reflections included
               in the _refln_ list should be given in the item
               _reflns_special_details.
;

data_reflns_observed_criterion
    _name                      '_reflns_observed_criterion'
    _category                    reflns
    _type                        char
    _related_item              '_reflns_threshold_expression'
    _related_function            replace
    _example                    'I>2u(I)'
    _definition
;              The criterion used to classify a reflection as 'observed'. This
               criterion is usually expressed in terms of a sigma(I) or sigma(F)
               threshold.
;

data_reflns_special_details
    _name                      '_reflns_special_details'
    _category                    reflns
    _type                        char
    _definition
;              Description of the properties of the reported reflection list
               that are not given in other data items.  In particular, this
               should include information about the averaging (or not) of
               symmetry-equivalent reflections including Friedel pairs.
;

data_reflns_threshold_expression
    _name                      '_reflns_threshold_expression'
    _category                    reflns
    _type                        char
    _related_item              '_reflns_observed_criterion'
    _related_function            alternate
    _example                    'I>2u(I)'
    _definition
;              The threshold, usually based on multiples of u(I), u(F^2^)
               or u(F), that serves to identify significantly intense
               reflections, the number of which is given by _reflns_number_gt.
               These reflections are used in the calculation of
               _refine_ls_R_factor_gt.
;

##################
## REFLNS_CLASS ##
##################

data_reflns_class_[]
    _name                        '_reflns_class_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
        _reflns_class_number_gt
        _reflns_class_code
               584     'Main'
               226     'Sat1'
               50      'Sat2'
;
;
    Example 1 - corresponding to the one-dimensional incommensurately
                modulated structure of K~2~SeO~4~.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      _definition
;              Data items in the REFLNS_CLASS category record details, for
               each reflection class, about the reflections used to determine
               the structural parameters.
;

data_reflns_class_code
    _name                      '_reflns_class_code'
    _category                    reflns_class
    _type                        char
    _list                        yes
    loop_ _list_link_child     '_refln_class_code' 
                               '_refine_ls_class_code'
    loop_ _example               '1'
                                 'm1'
                                 's2'
    _definition
;              The code identifying a certain reflection class.
;


data_reflns_class_d_res_high
    _name                      '_reflns_class_d_res_high'
    _category                    reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              For each reflection class, the highest resolution in angstroms
               for the reflections used in the refinement. This is the smallest
               d value.
;

data_reflns_class_d_res_low
    _name                      '_reflns_class_d_res_low'
    _category                    reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              For each reflection class, the lowest resolution in angstroms
               for the reflections used in the refinement. This is the largest
               d value.
;

data_reflns_class_description
    _name                      '_reflns_class_description'
    _category                    reflns_class
    _type                        char
    _list                        yes
    _list_reference            '_reflns_class_code'
    loop_ _example               'm=1 first order satellites'
                                 'H0L0 common projection reflections'
    _definition
;              Description of each reflection class.
;

data_reflns_class_number_gt
    _name                      '_reflns_class_number_gt'
    _category                    reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the number of significantly intense
               reflections (see _reflns_threshold_expression) in the _refln_
               list (not the _diffrn_refln_ list). This may include Friedel-
               equivalent reflections (i.e. those which are symmetry-equivalent
               under the Laue symmetry but inequivalent under the crystal
               class)  according to the nature of the structure and the
               procedures used. Special characteristics of the reflections
               included in the _refln_ list should be given in the item
               _reflns_special_details.
;

data_reflns_class_number_total
    _name                      '_reflns_class_number_total'
    _category                    reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the total number of reflections
               in the _refln_ list (not the _diffrn_refln_ list). This may
               include Friedel-equivalent reflections (i.e. those which are
               symmetry-equivalent under the Laue symmetry but inequivalent
               under the crystal class) according to the nature of the
               structure and the procedures used. Special characteristics
               of the reflections included in the _refln_ list should be given
               in the item _reflns_special_details.
;

data_reflns_class_R_factor_
    loop_ _name                '_reflns_class_R_factor_all'
                               '_reflns_class_R_factor_gt'
    _category                    reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factors for all
               reflections, and for significantly intense reflections (see
               _reflns_threshold_expression), included in the refinement.
               The reflections also satisfy the resolution limits established by
               _reflns_class_d_res_high and _reflns_class_d_res_low.
               This is the conventional R factor.

                   sum | F(obs) - F(calc) |
               R = ------------------------
                         sum | F(obs) |

               F(obs)  = the observed structure-factor amplitudes
               F(calc) = the calculated structure-factor amplitudes

               and the sum is taken over the reflections of this class. See also
               _reflns_class_wR_factor_all definitions.
;

data_reflns_class_R_Fsqd_factor
    _name                      '_reflns_class_R_Fsqd_factor'
    _category                    reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factor R(F^2^) calculated
               on the squared amplitudes of the observed and calculated
               structure factors, for the reflections judged significantly
               intense (i.e. satisfying the threshold specified by
               _reflns_threshold_expression) and included in the refinement.

               The reflections also satisfy the resolution limits established
               by _reflns_class_d_res_high and _reflns_class_d_res_low.

                          sum | F(obs)^2^ - F(calc)^2^ |
               R(Fsqd) = -------------------------------
                                  sum F(obs)^2^

               F(obs)^2^  = squares of the observed structure-factor amplitudes
               F(calc)^2^ = squares of the calculated structure-factor
                            amplitudes

               and the sum is taken over the reflections of this class.
;

data_reflns_class_R_I_factor
    _name                      '_reflns_class_R_I_factor'
    _category                    reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factor R(I) for the
               reflections judged significantly intense (i.e. satisfying the
               threshold specified by _reflns_threshold_expression) and
               included in the refinement.

               This is most often calculated in Rietveld refinements
               against powder data, where it is referred to as R~B~ or R~Bragg~.

                       sum | I(obs) - I(calc) |
               R(I) =  ------------------------
                              sum | I(obs) |

               I(obs)  = the net observed intensities
               I(calc) = the net calculated intensities

               and the sum is taken over the reflections of this class.
;

data_reflns_class_wR_factor_all
    _name                      '_reflns_class_wR_factor_all'
    _category                    reflns_class
    _type                        numb
    _list                        yes
    _list_reference            '_reflns_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the weighted residual factors for all
               reflections included in the refinement. The reflections also
               satisfy the resolution limits established by
               _reflns_class_d_res_high and _reflns_class_d_res_low.

                    ( sum w [ Y(obs) - Y(calc) ]^2^  )^1/2^
               wR = ( ------------------------------ )
                    (         sum w Y(obs)^2^       )

               Y(obs)  = the observed amplitudes specified by
                         _refine_ls_structure_factor_coef
               Y(calc) = the calculated amplitudes specified by
                         _refine_ls_structure_factor_coef
               w       = the least-squares weights

               and the sum is taken over the reflections of this class. See
               also _reflns_class_R_factor_ definitions.
;

##################
## REFLNS_SCALE ##
##################

data_reflns_scale_[]
    _name                      '_reflns_scale_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _reflns_scale_group_code
    _reflns_scale_meas_F
      1  .895447
      2  .912743

;
;
    Example 1 - based on standard test data set p6122 of the Xtal distribution
                [Hall, King & Stewart (1995). Xtal3.4 User's Manual. University
                of Western Australia].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the REFLNS_SCALE category record details about
               the structure-factor scales. They are referenced from within
               the REFLN list through _refln_scale_group_code.
;

data_reflns_scale_group_code
    _name                      '_reflns_scale_group_code'
    _category                    reflns_scale
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_child           '_refln_scale_group_code'
    _definition
;              The code identifying a scale _reflns_scale_meas_. These are
               linked to the _refln_ list by the _refln_scale_group_code. These
               codes need not correspond to those in the _diffrn_scale_ list.
;

data_reflns_scale_meas_
    loop_ _name                '_reflns_scale_meas_F'
                               '_reflns_scale_meas_F_squared'
                               '_reflns_scale_meas_intensity'
    _category                    reflns_scale
    _type                        numb
    _type_conditions             esd
    _enumeration_range           0.0:
    _list                        yes
    _list_reference            '_reflns_scale_group_code'
    _definition
;              Scales associated with _reflns_scale_group_code.
;

##################
## REFLNS_SHELL ##
##################

data_reflns_shell_[]
    _name                      '_reflns_shell_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _reflns_shell_d_res_high
    _reflns_shell_d_res_low
    _reflns_shell_meanI_over_uI_gt
    _reflns_shell_number_measured_gt
    _reflns_shell_number_unique_gt
    _reflns_shell_percent_possible_gt
    _reflns_shell_Rmerge_F_gt
      31.38  3.82  69.8  9024  2540  96.8   1.98
       3.82  3.03  26.1  7413  2364  95.1   3.85
       3.03  2.65  10.5  5640  2123  86.2   6.37
       2.65  2.41   6.4  4322  1882  76.8   8.01
       2.41  2.23   4.3  3247  1714  70.4   9.86
       2.23  2.10   3.1  1140   812  33.3  13.99
;
;
    Example 1 - based on PDB entry 5HVP and laboratory records for the
                structure corresponding to PDB entry 5HVP.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the REFLNS_SHELL category record details about
               the reflections used to determine the ATOM_SITE data items,
               as broken down by shells of resolution.
;

data_reflns_shell_d_res_high
    _name                      '_reflns_shell_d_res_high'
    _category                    reflns_shell
    _type                        numb
    _list                        yes
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The highest resolution in angstroms for the reflections in
               this shell. This is the smallest d value.
;

data_reflns_shell_d_res_low
    _name                      '_reflns_shell_d_res_low'
    _category                    reflns_shell
    _type                        numb
    _list                        yes
    _enumeration_range           0.0:
    _units                       A
    _units_detail              'angstroms'
    _definition
;              The lowest resolution in angstroms for the
               reflections in this shell. This is the largest d value.
;

data_reflns_shell_meanI_over_sigI_all
    _name                      '_reflns_shell_meanI_over_sigI_all'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_meanI_over_uI_all'
    _related_function            replace
    _list                        yes
    _definition
;              The ratio of the mean of the intensities of all reflections
               in this shell to the mean of the standard uncertainties of the
               intensities of all reflections in the resolution shell.
;

data_reflns_shell_meanI_over_sigI_gt
    _name                      '_reflns_shell_meanI_over_sigI_gt'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_meanI_over_uI_gt'
    _related_function            replace
    _list                        yes
    _definition
;              The ratio of the mean of the intensities of the significantly
               intense reflections (see _reflns_threshold_expression) in
               this shell to the mean of the standard uncertainties of the
               intensities of the significantly intense reflections in the
               resolution shell.
;

data_reflns_shell_meanI_over_sigI_obs
    _name                      '_reflns_shell_meanI_over_sigI_obs'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_meanI_over_sigI_gt'
    _related_function            replace
    _list                        yes
    _definition
;              The ratio of the mean of the intensities of the reflections
               classified as 'observed' (see _reflns_observed_criterion) in
               this shell to the mean of the standard uncertainties of the
               intensities of the 'observed' reflections in the resolution
               shell.
;

data_reflns_shell_meanI_over_uI_all
    _name                      '_reflns_shell_meanI_over_uI_all'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_meanI_over_sigI_all'
    _related_function            alternate
    _list                        yes
    _definition
;              The ratio of the mean of the intensities of all reflections
               in this shell to the mean of the standard uncertainties of the
               intensities of all reflections in the resolution shell.
;

data_reflns_shell_meanI_over_uI_gt
    _name                      '_reflns_shell_meanI_over_uI_gt'
    _category                    reflns_shell
    _type                        numb
    loop_ _related_item
          _related_function    '_reflns_shell_meanI_over_sigI_gt'   alternate
                               '_reflns_shell_meanI_over_sigI_obs'  alternate
    _list                        yes
    _definition
;              The ratio of the mean of the intensities of the significantly
               intense reflections (see _reflns_threshold_expression) in
               this shell to the mean of the standard uncertainties of the
               intensities of the significantly intense reflections in the
               resolution shell.
;


data_reflns_shell_number_measured_all
    _name                      '_reflns_shell_number_measured_all'
    _category                    reflns_shell
    _type                        numb
    _list                        yes
    _enumeration_range           0.0:
    _definition
;              The total number of reflections measured for this
               resolution shell.
;

data_reflns_shell_number_measured_gt
    _name                      '_reflns_shell_number_measured_gt'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_number_measured_obs'
    _related_function            alternate
    _list                        yes
    _enumeration_range           0.0:
    _definition
;              The number of significantly intense reflections
               (see _reflns_threshold_expression) measured for this
               resolution shell.
;

data_reflns_shell_number_measured_obs
    _name                      '_reflns_shell_number_measured_obs'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_number_measured_gt'
    _related_function            replace
    _list                        yes
    _enumeration_range           0.0:
    _definition
;              The number of reflections classified as 'observed'
               (see _reflns_observed_criterion) measured for this
               resolution shell.
;

data_reflns_shell_number_possible
    _name                      '_reflns_shell_number_possible'
    _category                    reflns_shell
    _type                        numb
    _list                        yes
    _enumeration_range           0:
    _definition
;              The number of unique reflections it is possible to measure in
               this reflection shell.
;

data_reflns_shell_number_unique_all
    _name                      '_reflns_shell_number_unique_all'
    _category                    reflns_shell
    _type                        numb
    _list                        yes
    _enumeration_range           0:
    _definition
;              The total number of measured reflections resulting from
               merging measured symmetry-equivalent reflections for this
               resolution shell.
;

data_reflns_shell_number_unique_gt
    _name                      '_reflns_shell_number_unique_gt'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_number_unique_obs'
    _related_function            alternate
    _list                        yes
    _enumeration_range           0:
    _definition
;              The total number of significantly intense reflections
               (see _reflns_threshold_expression) resulting from merging
               measured symmetry-equivalent reflections for this resolution
               shell.
;

data_reflns_shell_number_unique_obs
    _name                      '_reflns_shell_number_unique_obs'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_number_unique_gt'
    _related_function            replace
    _list                        yes
    _enumeration_range           0:
    _definition
;              The total number of reflections classified as
               'observed' (see _reflns_observed_criterion) resulting from
               merging measured symmetry-equivalent reflections for this
               resolution shell.
;

data_reflns_shell_percent_possible_all
    _name                      '_reflns_shell_percent_possible_all'
    _category                    reflns_shell
    _type                        numb
    _list                        yes
    _enumeration_range           0.0:100.0
    _definition
;              The percentage of geometrically possible reflections
               represented by all reflections measured for this
               resolution shell.
;

data_reflns_shell_percent_possible_gt
    _name                      '_reflns_shell_percent_possible_gt'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_percent_possible_obs'
    _related_function            alternate
    _list                        yes
    _enumeration_range           0.0:100.0
    _definition
;              The percentage of geometrically possible reflections
               represented by significantly intense reflections
               (see _reflns_threshold_expression) measured for this
               resolution shell.
;

data_reflns_shell_percent_possible_obs
    _name                      '_reflns_shell_percent_possible_obs'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_percent_possible_gt'
    _related_function            replace
    _list                        yes
    _enumeration_range           0.0:100.0
    _definition
;              The percentage of geometrically possible reflections
               represented by reflections classified as 'observed'
               (see _reflns_observed_criterion) measured for this
               resolution shell.
;

data_reflns_shell_Rmerge_F_all
    _name                      '_reflns_shell_Rmerge_F_all'
    _category                    reflns_shell
    _type                        numb
    _list                        yes
    _enumeration_range           0.0:
    _definition
;              The value of Rmerge(F) for all reflections in a given shell.

                           sum~i~ ( sum~j~ | F~j~ - <F> | )
               Rmerge(F) = --------------------------------
                               sum~i~ ( sum~j~ <F> )

               F~j~  = the amplitude of the jth observation of reflection i
               <F> = the mean of the amplitudes of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

data_reflns_shell_Rmerge_F_gt
    _name                      '_reflns_shell_Rmerge_F_gt'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_Rmerge_F_obs'
    _related_function            alternate
    _list                        yes
    _enumeration_range           0.0:
    _definition
;              The value of Rmerge(F) for significantly intense reflections
               (see _reflns_threshold_expression) in a given shell.

                           sum~i~ ( sum~j~ | F~j~ - <F> | )
               Rmerge(F) = --------------------------------
                               sum~i~ ( sum~j~ <F> )

               F~j~  = the amplitude of the jth observation of reflection i
               <F> = the mean of the amplitudes of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

data_reflns_shell_Rmerge_F_obs
    _name                      '_reflns_shell_Rmerge_F_obs'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_Rmerge_F_gt'
    _related_function            replace
    _list                        yes
    _enumeration_range           0.0:
    _definition
;              The value of Rmerge(F) for reflections classified as 'observed'
               (see _reflns_observed_criterion) in a given shell.

                           sum~i~ ( sum~j~ | F~j~ - <F> | )
               Rmerge(F) = --------------------------------
                               sum~i~ ( sum~j~ <F> )

               F~j~  = the amplitude of the jth observation of reflection i
               <F> = the mean of the amplitudes of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

data_reflns_shell_Rmerge_I_all
    _name                      '_reflns_shell_Rmerge_I_all'
    _category                    reflns_shell
    _type                        numb
    _list                        yes
    _enumeration_range           0.0:
    _definition
;              The value of Rmerge(I) for all reflections in a given shell.

                           sum~i~ ( sum~j~ | I~j~ - <I> | )
               Rmerge(I) = --------------------------------
                               sum~i~ ( sum~j~ <I> )

               I~j~  = the intensity of the jth observation of reflection i
               <I> = the mean of the intensities of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

data_reflns_shell_Rmerge_I_gt
    _name                      '_reflns_shell_Rmerge_I_gt'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_Rmerge_I_obs'
    _related_function            alternate
    _list                        yes
    _enumeration_range           0.0:
    _definition
;              The value of Rmerge(I) for significantly intense reflections
               (see _reflns_threshold_expression) in a given shell.

                           sum~i~ ( sum~j~ | I~j~ - <I> | )
               Rmerge(I) = --------------------------------
                               sum~i~ ( sum~j~ <I> )

               I~j~  = the intensity of the jth observation of reflection i
               <I> = the mean of the intensities of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

data_reflns_shell_Rmerge_I_obs
    _name                      '_reflns_shell_Rmerge_I_obs'
    _category                    reflns_shell
    _type                        numb
    _related_item              '_reflns_shell_Rmerge_I_gt'
    _related_function            replace
    _list                        yes
    _enumeration_range           0.0:
    _definition
;              The value of Rmerge(I) for reflections classified as 'observed'
               (see _reflns_observed_criterion) in a given shell.

                           sum~i~ ( sum~j~ | I~j~ - <I> | )
               Rmerge(I) = --------------------------------
                               sum~i~ ( sum~j~ <I> )

               I~j~  = the intensity of the jth observation of reflection i
               <I> = the mean of the intensities of all observations of
                      reflection i

               sum~i~ is taken over all reflections
               sum~j~ is taken over all observations of each reflection.
;

#################
## SPACE_GROUP ##
#################

data_space_group_[]
    _name                      '_space_group_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
    _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _space_group_id                 1
    _space_group_name_H-M_alt       'C 2/c'
    _space_group_IT_number          15
    _space_group_name_Hall          '-C 2yc'
    _space_group_crystal_system     monoclinic
;
;
    Example 1 - the monoclinic space group No. 15 with unique axis b.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Contains all the data items that refer to the space group as a
               whole, such as its name or crystal system. They may be looped,
               for example, in a list of space groups and their properties.

               Only a subset of the SPACE_GROUP category items appear in the
               core dictionary.  The remainder are found in the symmetry CIF
               dictionary.

               Space-group types are identified by their number as given in
               International Tables for Crystallography Vol. A. Specific
               settings of the space groups can be identified either by their
               Hall symbol or by specifying their symmetry operations.

               The commonly used Hermann-Mauguin symbol determines the
               space-group type uniquely but several different Hermann-Mauguin
               symbols may refer to the same space-group type. A
               Hermann-Mauguin symbol contains information on the choice of
               the basis, but not on the choice of origin.  Different formats
               for the Hermann-Mauguin symbol are found in the symmetry CIF
               dictionary.
;


data_space_group_crystal_system
    _name                      '_space_group_crystal_system'
    _category                   space_group
    _type                       char
    _list                       both
    _list_reference            '_space_group_id'
    _related_item              '_symmetry_cell_setting'
    _related_function            alternate
    loop_ _enumeration           triclinic
                                 monoclinic
                                 orthorhombic
                                 tetragonal
                                 trigonal
                                 hexagonal
                                 cubic
    _definition
;              The name of the system of geometric crystal classes of space
               groups (crystal system) to which the space group belongs.
               Note that rhombohedral space groups belong to the
               trigonal system.
;

data_space_group_id
    _name                      '_space_group_id'
    _category                    space_group
    _type                        char
    _list                        yes
    _list_mandatory              yes
    _list_link_child           '_space_group_symop_sg_id'
    _definition
;              This is an identifier needed if _space_group_ items are looped.
;

data_space_group_IT_number
    _name                      '_space_group_IT_number'
    _category                    space_group
    _type                        numb
    _list                        both
    _list_reference            '_space_group_id'
    _related_item              '_symmetry_Int_Tables_number'
    _related_function            alternate
    _enumeration_range           1:230
    _definition
;              The number as assigned in International Tables for
               Crystallography Vol. A, specifying the proper affine class (i.e.
               the orientation-preserving affine class) of space groups
               (crystallographic space-group type) to which the space group
               belongs.  This number defines the space-group type but not
               the coordinate system in which it is expressed.
;

data_space_group_name_H-M_alt
    _name                      '_space_group_name_H-M_alt'
    _category                    space_group
    _type                        char
    _list                        both
    _list_reference            '_space_group_id'
    _related_item              '_symmetry_space_group_name_H-M'
    _related_function            alternate
    loop_ _example
          _example_detail
;                                loop_
                                   _space_group_id
                                   _space_group_name_H-M_alt
                                    1    'C m c m'
                                    2    'C 2/c 2/m 21/m'
                                    3    'A m a m'
;
                               'three examples for space group No. 63'
    _definition
;              _space_group_name_H-M_alt allows any Hermann-Mauguin symbol
               to be given. The way in which this item is used is determined
               by the user and in general is not intended to be interpreted by
               computer. It may, for example, be used to give one of the
               extended Hermann-Mauguin symbols given in Table 4.3.2.1 of
               International Tables for Crystallography Vol. A (2002) or
               a Hermann-Mauguin symbol for a conventional or unconventional
               setting.

               Each component of the space-group name is separated by a
               space or an underscore. The use of a space is strongly
               recommended.  The underscore is only retained because it
               was used in older files. It should not be
               used in new CIFs. Subscripts should appear without special
               symbols. Bars should be given as negative signs before the
               numbers to which they apply.

               The commonly used Hermann-Mauguin symbol determines the space-
               group type uniquely but a given space-group type may be
               described by more than one Hermann-Mauguin symbol. The space-
               group type is best described using _space_group_IT_number.

               The Hermann-Mauguin symbol may contain information on the
               choice of basis, but not on the choice of origin. To
               define the setting uniquely, use _space_group_name_Hall or
               list the symmetry operations.
;

data_space_group_name_Hall
    _name                      '_space_group_name_Hall'
    _category                    space_group
    _type                        char
    _list                        both
    _list_reference            '_space_group_id'
    _related_item              '_symmetry_space_group_name_Hall'
    _related_function            alternate
    loop_ _example
          _example_detail      'P 2c -2ac'            'equivalent to Pca21'
                               '-I 4bd 2ab 3'         'equivalent to Ia-3d'
    _definition
;              Space-group symbol defined by Hall.

               Each component of the space-group name is separated by a
               space or an underscore.  The use of a space is strongly
               recommended.  The underscore is only retained because it
               was used in older files.  It should not be
               used in new CIFs.

               _space_group_name_Hall uniquely defines the space group and
               its reference to a particular coordinate system.

               Ref: Hall, S. R. (1981). Acta Cryst. A37, 517-525; erratum
                    (1981), A37, 921.
                    [See also International Tables for Crystallography,
                    Vol. B (2001), Chapter 1.4, Appendix 1.4.2]
;

#######################
## SPACE_GROUP_SYMOP ##
#######################

data_space_group_symop_[]
    _name                      '_space_group_symop_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;   loop_
    _space_group_symop_id
    _space_group_symop_operation_xyz
      1    x,y,z
      2   -x,-y,-z
      3   -x,1/2+y,1/2-z
      4    x,1/2-y,1/2+z
;
;
    Example 1 - the symmetry operations for the space group P21/c.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Contains information about the symmetry operations of the
               space group.
;

data_space_group_symop_id
    _name                      '_space_group_symop_id'
    _type                        char
    _category                    space_group_symop
    _list                        yes
    _list_mandatory              yes
    _enumeration_default         1
    _related_item              '_symmetry_equiv_pos_site_id'
    _related_function            alternate
    _definition
;              An arbitrary identifier that uniquely labels each symmetry
               operation in the list.

               In order for the defaults to work correctly, the identity
               operation should have _space_group_symop_id or
               _symmetry_equiv_pos_site_id set to 1, and
               _space_group_symop_operation_xyz or
               _symmetry_equiv_pos_as_xyz set to x,y,z; 
               i.e. the operation labelled 1 should be the identity
               operation.
;


data_space_group_symop_operation_xyz
    _name                      '_space_group_symop_operation_xyz'
    _category                    space_group_symop
    _type              char
    _list                        both
    _list_reference            '_space_group_symop_id'
    _enumeration_default       'x,y,z'
    _related_item              '_symmetry_equiv_pos_as_xyz'
    _related_function            alternate
    loop_ _example
    _example_detail            'x,1/2-y,1/2+z'
;                                glide reflection through the plane (x,1/4,z),
                                 with glide vector (1/2)c
;
    _definition
;               A parsable string giving one of the symmetry operations of the
                space group in algebraic form.  If W is a matrix representation
                of the rotational part of the symmetry operation defined by the
                positions and signs of x, y and z, and w is a column of
                translations defined by fractions, an equivalent position
                X' is generated from a given position X by the equation

                          X' = WX + w

                (Note: X is used to represent bold_italics_x in International
                Tables for Crystallography Vol. A, Part 5)

                When a list of symmetry operations is given, it must contain
                a complete set of coordinate representatives which generates
                all the operations of the space group by the addition of
                all primitive translations of the space group. Such
                representatives are to be found as the coordinates of
                the general-equivalent position in International Tables for
                Crystallography Vol. A (2002), to which it is necessary to 
                add any centring translations shown above the 
                general-equivalent position.

                That is to say, it is necessary to list explicitly all the
                symmetry operations required to generate all the atoms in
                the unit cell defined by the setting used.

               In order for the defaults to work correctly, the identity
               operation should have _space_group_symop_id or
               _symmetry_equiv_pos_site_id set to 1, and
               _space_group_symop_operation_xyz or
               _symmetry_equiv_pos_as_xyz set to x,y,z; 
               i.e. the operation labelled 1 should be the identity
               operation.
;

data_space_group_symop_sg_id
    _name                      '_space_group_symop_sg_id'
    _category                    space_group_symop
    _type                        numb
    _list                        both
    _list_mandatory              no
    _list_reference            '_space_group_symop_id'
    _list_link_parent          '_space_group_id'
    _definition
;              This must match a particular value of _space_group_id, allowing
               the symmetry operation to be identified with a particular space
               group.
;

##############
## SYMMETRY ##
##############

data_symmetry_[]
    _name                      '_symmetry_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    _symmetry_cell_setting             orthorhombic
    _symmetry_space_group_name_H-M     'P 21 21 21'
    _symmetry_space_group_name_Hall    'P 2ac 2ab'
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the SYMMETRY category record details about the
               space-group symmetry.
;

data_symmetry_cell_setting
    _name                      '_symmetry_cell_setting'
    _category                    symmetry
    _type                        char
    loop_ _enumeration           triclinic
                                 monoclinic
                                 orthorhombic
                                 tetragonal
                                 rhombohedral
                                 trigonal
                                 hexagonal
                                 cubic
    _related_item              '_space_group_crystal_system'
    _related_function            replace
    _definition
;              The cell settings for this space-group symmetry.
;

data_symmetry_Int_Tables_number
    _name                      '_symmetry_Int_Tables_number'
    _category                    symmetry
    _type                        numb
    _enumeration_range           1:230
    _related_item              '_space_group_IT_number'
    _related_function            replace
    _definition
;              Space-group number from International Tables for Crystallography
               Vol. A (2002).
;


data_symmetry_space_group_name_H-M
    _name                      '_symmetry_space_group_name_H-M'
    _category                    symmetry
    _type                        char
    _related_item              '_space_group_name_H-M_alt'
    _related_function            replace
    loop_ _example              'P 1 21/m 1'
                                'P 2/n 2/n 2/n (origin at -1)'
                                'R -3 2/m'
    _definition
;             Hermann-Mauguin space-group symbol. Note that the Hermann-Mauguin
              symbol does not necessarily contain complete information
              about the symmetry and the space-group origin. If used, always
              supply the FULL symbol from International Tables for
              Crystallography Vol. A (2002) and indicate the origin and
              the setting if it is not implicit. If there is any doubt
              that the equivalent positions can be uniquely deduced from
              this symbol, specify the _symmetry_equiv_pos_as_xyz
              or *_Hall data items as well. Leave spaces between
              symbols referring to different axes.

;

data_symmetry_space_group_name_Hall
    _name                      '_symmetry_space_group_name_Hall'
    _category                    symmetry
    _type                        char
    _related_item              '_space_group_name_Hall'
    _related_function            replace
    loop_ _example             '-P 2ac 2n'
                               '-R 3 2"'
                               'P 61 2 2 (0 0 -1)'
    _definition
;              Space-group symbol as described by Hall. This symbol gives the
               space-group setting explicitly. Leave spaces between the separate
               components of the symbol.

               Ref: Hall, S. R. (1981). Acta Cryst. A37, 517-525; erratum
               (1981), A37, 921.
;

####################
## SYMMETRY_EQUIV ##
####################

data_symmetry_equiv_[]
    _name                      '_symmetry_equiv_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _symmetry_equiv_pos_as_xyz
        +x,+y,+z  1/2-x,-y,1/2+z  1/2+x,1/2-y,-z  -x,1/2+y,1/2-z
;
;
    Example 1 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277].
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _symmetry_equiv_pos_site_id
    _symmetry_equiv_pos_as_xyz
        1     x,y,z
        2     1/2-x,-y,1/2+z
        3     1/2+x,1/2-y,-z
        4     -x,1/2+y,1/2-z

;
;
    Example 2 - based on data set TOZ of Willis, Beckwith & Tozer
                [Acta Cryst. (1991), C47, 2276-2277]. Formally, the value of
                _symmetry_equiv_pos_site_id can be any unique character string;
                it is recommended that it be assigned the sequence number of
                the list of equivalent positions for compatibility with
                older files in which it did not appear.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the SYMMETRY_EQUIV category list the
               symmetry-equivalent positions for the space group.
;

data_symmetry_equiv_pos_as_xyz
    _name                      '_symmetry_equiv_pos_as_xyz'
    _category                    symmetry_equiv
    _type                        char
    _list                        both
    _enumeration_default         x,y,z
    _example                     -y+x,-y,1/3+z
    _related_item              '_space_group_symop_operation_xyz'
    _related_function            replace
    _definition
;              Symmetry-equivalent position in the 'xyz' representation. Except
               for the space group P1, these data will be repeated in a loop.
               The format of the data item is as per International Tables for
               Crystallography Vol. A. (2002). All equivalent positions should
               be entered, including those for lattice centring and a centre of
               symmetry, if present.

               In order for the defaults to work correctly, the identity
               operation should have _space_group_symop_id or
               _symmetry_equiv_pos_site_id set to 1, and
               _space_group_symop_operation_xyz or
               _symmetry_equiv_pos_as_xyz set to x,y,z; 
               i.e. the operation labelled 1 should be the identity
               operation.
;

data_symmetry_equiv_pos_site_id
    _name                      '_symmetry_equiv_pos_site_id'
    _category                    symmetry_equiv
    _type                        numb
    _list                        yes
    _list_reference            '_symmetry_equiv_pos_as_xyz'
    _enumeration_default         1
    _related_item              '_space_group_symop_id'
    _related_function            replace
    _definition
;              A code identifying each entry in the _symmetry_equiv_pos_as_xyz
               list. It is normally the sequence number of the entry in that
               list, and should be identified with the code 'n' in
               _geom_*_symmetry_ codes of the form 'n_klm'.

               In order for the defaults to work correctly, the identity
               operation should have _space_group_symop_id or
               _symmetry_equiv_pos_site_id set to 1, and
               _space_group_symop_operation_xyz or
               _symmetry_equiv_pos_as_xyz set to x,y,z; 
               i.e. the operation labelled 1 should be the identity
               operation.
;

###################
## VALENCE_PARAM ##
###################

data_valence_param_[]
    _name                      '_valence_param_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    loop_
    _valence_param_id
    _valence_param_atom_1
    _valence_param_atom_1_valence
    _valence_param_atom_2
    _valence_param_atom_2_valence
    _valence_param_Ro
    _valence_param_B
    _valence_param_ref_id
    _valence_param_details
      1   Cu 2 O -2 1.679 0.37 a .
      2   Cu 2 O -2 1.649 0.37 j .
      3   Cu 2 N -3 1.64  0.37 m '2-coordinate N'
      4   Cu 2 N -3 1.76  0.37 m '3-coordinate N'
    loop_
    _valence_ref_id
    _valence_ref_reference
      a  'Brown & Altermatt (1985), Acta Cryst. B41, 244-247'
      j  'Liu & Thorp (1993), Inorg. Chem. 32, 4102-4205'
      m  'See, Krause & Strub (1998), Inorg. Chem. 37, 5369-5375'
;
;
    Example 1 - a bond-valence parameter list with accompanying references.
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    _definition
;              Data items in the VALENCE_PARAM category define the
               parameters used for calculating bond valences from bond
               lengths.  In addition to the parameters, a pointer
               is given to the reference (in VALENCE_REF) from which
               the bond-valence parameters were taken.
;

data_valence_param_atom_1
    _name                      '_valence_param_atom_1'
    _category                    valence_param
    _type                        char
    _list                        yes
    _list_reference            '_valence_param_id'
    _definition
;              The element symbol of the first atom forming the bond whose
               bond-valence parameters are given in this category.
;

data_valence_param_atom_1_valence
    _name                      '_valence_param_atom_1_valence'
    _category                    valence_param
    _type                        numb
    _list                        yes
    _list_reference            '_valence_param_id'
    _definition
;              The valence (formal charge) of the first atom whose
               bond-valence parameters are given in this category.
;

data_valence_param_atom_2
    _name                      '_valence_param_atom_2'
    _category                    valence_param
    _type                        char
    _list                        yes
    _list_reference            '_valence_param_id'
    _definition
;              The element symbol of the second atom forming the bond whose
               bond-valence parameters are given in this category.
;

data_valence_param_atom_2_valence
    _name                      '_valence_param_atom_2_valence'
    _category                    valence_param
    _type                        numb
    _list                        yes
    _list_reference            '_valence_param_id'
    _definition
;              The valence (formal charge) of the second atom whose
               bond-valence parameters are given in this category.
;

data_valence_param_B
    _name                      '_valence_param_B'
    _category                    valence_param
    _type                        numb
    _list                        yes
    _list_reference            '_valence_param_id'
    _units                       A
    _units_detail                Angstrom
    _definition
;              The bond-valence parameter B used in the expression

                     s = exp[(Ro - R)/B]

               where s is the valence of a bond of length R.
;

data_valence_param_details
    _name                      '_valence_param_details'
    _category                    valence_param
    _type                        char
    _list                        yes
    _list_reference            '_valence_param_id'
    _definition
;              Details of or comments on the bond-valence parameters.
;

data_valence_param_id
    _name                      '_valence_param_id'
    _category                    valence_param
    _type                        char
    _list                        yes
    _definition
;              An identifier for the valence parameters of a bond between
               the given atoms.
;

data_valence_param_ref_id
    _name                      '_valence_param_ref_id'
    _category                     valence_param
    _type                         char
    _list                         yes
    _list_reference             '_valence_param_id'
    _list_link_parent           '_valence_ref_id'
    _definition
;              An identifier which links to the reference to the source
               from which the bond-valence parameters are taken. A child
               of _valence_ref_id, which it must match.
;

data_valence_param_Ro
    _name                      '_valence_param_Ro'
    _category                    valence_param
    _type                        numb
    _list                        yes
    _list_reference            '_valence_param_id'
    _units                       A
    _units_detail                Angstrom
    _definition
;              The bond-valence parameter Ro used in the expression

                     s = exp[(Ro - R)/B]

               where s is the valence of a bond of length R.
;

#################
## VALENCE_REF ##
#################

data_valence_ref_[]
    _name                      '_valence_ref_[]'
    _category                    category_overview
    _type                        null
    _definition
;              Data items in the VALENCE_REF category list the references
               from which the bond-valence parameters have been taken.
;

data_valence_ref_id
    _name                      '_valence_ref_id'
    _category                    valence_ref
    _type                        char
    _list                        yes
    _list_reference            '_valence_ref_id'
    _list_link_child           '_valence_param_ref_id'
    _definition
;              An identifier for items in this category. Parent of
               _valence_param_ref_id, which must have the same value.
;

data_valence_ref_reference
    _name                      '_valence_ref_reference'
    _type                        char
    _category                    valence_ref
    _list                        yes
    _list_reference            '_valence_ref_id'
    _definition
;              Literature reference from which the valence parameters
               identified by _valence_param_id were taken.
;

#-eof-eof-eof-eof-eof-eof-eof-eof-eof-eof-eof-eof-eof-eof-eof-eof-eof-eof-eof
