ST_AsMARC21

Returns geometry as a MARC21/XML record with a geographic datafield (034).

                        text
                        ST_AsMARC21

                        geometry
                        geom

                        text
                        format='hdddmmss'

## Description

This function returns a MARC21/XML record with Coded Cartographic Mathematical Data representing the bounding box of a given geometry. The `format` parameter allows to encode the coordinates in subfields `$d`,`$e`,`$f` and `$g` in all formats supported by the MARC21/XML standard. Valid formats are:

- cardinal direction, degrees, minutes and seconds (default): `hdddmmss`

- decimal degrees with cardinal direction: `hddd.dddddd`

- decimal degrees without cardinal direction: `ddd.dddddd`

- decimal minutes with cardinal direction: `hdddmm.mmmm`

- decimal minutes without cardinal direction: `dddmm.mmmm`

- decimal seconds with cardinal direction: `hdddmmss.sss`

The decimal sign may be also a comma, e.g. `hdddmm,mmmm`.

The precision of decimal formats can be limited by the number of characters after the decimal sign, e.g. `hdddmm.mm` for decimal minutes with a precision of two decimals.

This function ignores the Z and M dimensions.

LOC MARC21/XML versions supported:

- MARC21/XML 1.1

Availability: 3.3.0

This function does not support non lon/lat geometries, as they are not supported by the MARC21/XML standard (Coded Cartographic Mathematical Data).

The MARC21/XML Standard does not provide any means to annotate the spatial reference system for Coded Cartographic Mathematical Data, which means that this information will be lost after conversion to MARC21/XML.

## Examples

Converting a `POINT` to MARC21/XML formated as hdddmmss (default)

                SELECT ST_AsMARC21('SRID=4326;POINT(-4.504289 54.253312)'::geometry);

                                  st_asmarc21
                -------------------------------------------------
                <record xmlns="http://www.loc.gov/MARC21/slim">
                    <datafield tag="034" ind1="1" ind2=" ">
                        <subfield code="a">a</subfield>
                        <subfield code="d">W0043015</subfield>
                        <subfield code="e">W0043015</subfield>
                        <subfield code="f">N0541512</subfield>
                        <subfield code="g">N0541512</subfield>
                    </datafield>
                </record>

Converting a `POLYGON` to MARC21/XML formated in decimal degrees

                SELECT ST_AsMARC21('SRID=4326;POLYGON((-4.5792388916015625 54.18172660239091,-4.56756591796875 54.196993557130355,-4.546623229980469 54.18313300502024,-4.5792388916015625 54.18172660239091))'::geometry,'hddd.dddd');

                <record xmlns="http://www.loc.gov/MARC21/slim">
                    <datafield tag="034" ind1="1" ind2=" ">
                        <subfield code="a">a</subfield>
                        <subfield code="d">W004.5792</subfield>
                        <subfield code="e">W004.5466</subfield>
                        <subfield code="f">N054.1970</subfield>
                        <subfield code="g">N054.1817</subfield>
                    </datafield>
                </record>

Converting a `GEOMETRYCOLLECTION` to MARC21/XML formated in decimal minutes. The geometries order in the MARC21/XML output correspond to their order in the collection.

                SELECT ST_AsMARC21('SRID=4326;GEOMETRYCOLLECTION(POLYGON((13.1 52.65,13.516666666666667 52.65,13.516666666666667 52.38333333333333,13.1 52.38333333333333,13.1 52.65)),POINT(-4.5 54.25))'::geometry,'hdddmm.mmmm');

                                  st_asmarc21
                -------------------------------------------------
                <record xmlns="http://www.loc.gov/MARC21/slim">
                    <datafield tag="034" ind1="1" ind2=" ">
                        <subfield code="a">a</subfield>
                        <subfield code="d">E01307.0000</subfield>
                        <subfield code="e">E01331.0000</subfield>
                        <subfield code="f">N05240.0000</subfield>
                        <subfield code="g">N05224.0000</subfield>
                    </datafield>
                    <datafield tag="034" ind1="1" ind2=" ">
                        <subfield code="a">a</subfield>
                        <subfield code="d">W00430.0000</subfield>
                        <subfield code="e">W00430.0000</subfield>
                        <subfield code="f">N05415.0000</subfield>
                        <subfield code="g">N05415.0000</subfield>
                    </datafield>
                </record>

## See Also

ST_GeomFromMARC21