Control files and their fields
==============================

The package management system manipulates data represented in a common
format, known as *control data*, stored in *control files*. Control
files are used for source packages, binary packages and the ``.changes``
files which control the installation of uploaded files.  [#]_

.. _s-controlsyntax:

Syntax of control files
-----------------------

A control file consists of one or more stanzas of fields.  [#]_ The
stanzas are separated by empty lines. Parsers may accept lines
consisting solely of spaces and tabs as stanza separators, but
control files should use empty lines. Some control files allow only one
stanza; others allow several, in which case each stanza usually
refers to a different package. (For example, in source packages, the
first stanza refers to the source package, and later stanzas refer
to binary packages generated from the source.) The ordering of the
stanzas in control files is significant.

Each stanza consists of a series of data fields. Each field consists
of the field name followed by a colon and then the data/value associated
with that field. The field name is composed of US-ASCII characters
excluding control characters, space, and colon (i.e., characters in the
ranges U+0021 (``!``) through U+0039 (``9``), and U+003B (``;``) through
U+007E (``~``), inclusive). Field names must not begin with the comment
character (U+0023 ``#``), nor with the hyphen character (U+002D ``-``).

The field ends at the end of the line or at the end of the last
continuation line (see below). Horizontal whitespace (spaces and tabs)
may occur immediately before or after the value and is ignored there; it
is conventional to put a single space after the colon. For example, a
field might be:

::

    Package: libc6

the field name is ``Package`` and the field value ``libc6``.

Empty field values are only permitted in source package template
control files (``debian/control``). Such fields are ignored.

A stanza must not contain more than one instance of a particular
field name.

There are three types of fields:

simple
    The field, including its value, must be a single line. Folding of
    the field is not permitted. This is the default field type if the
    definition of the field does not specify a different type.

folded
    The value of a folded field is a logical line that may span several
    lines. The lines after the first are called continuation lines and
    must start with a space or a tab. Whitespace, including any
    newlines, is not significant in the field values of folded fields.  [#]_

multiline
    The value of a multiline field may comprise multiple continuation
    lines. The first line of the value, the part on the same line as the
    field name, often has special significance or may have to be empty.
    Other lines are added following the same syntax as the continuation
    lines of the folded fields. Whitespace, including newlines, is
    significant in the values of multiline fields.

Whitespace must not appear inside names (of packages, architectures,
files or anything else) or version numbers, or between the characters of
multi-character version relationships.

The presence and purpose of a field, and the syntax of its value, may
differ between types of control files.

Field names are not case-sensitive, but it is usual to capitalize the
field names using mixed case as shown below. Field values are
case-sensitive unless the description of the field says otherwise.

Stanza separators (empty lines), and lines consisting only of U+0020
SPACE and U+0009 TAB, are not allowed within field values or between
fields. Empty lines in field values are usually escaped by representing
them by a U+0020 SPACE followed by a U+002E (``.``).

Lines starting with U+0023 (``#``), without any preceding whitespace,
are comment lines that are only permitted in source package control
files (``debian/control``). These comment lines are ignored, even
between two continuation lines. They do not end logical lines.

All control files must be encoded in UTF-8.

.. _s-sourcecontrolfiles:

Debian source package template control files -- ``debian/control``
------------------------------------------------------------------

The ``debian/control`` file contains the most vital (and
version-independent) information about the source package and about the
binary packages it creates.

The first stanza of the control file contains information about the
source package in general. The subsequent stanzas each describe a
binary package that the source tree builds. Each binary package built
from this source package has a corresponding stanza, except for any
automatically-generated debug packages that do not require one.

The fields in the source package stanza (the first one) are:

-  :ref:`Source <s-f-Source>` (mandatory)

-  :ref:`Maintainer <s-f-Maintainer>` (mandatory)

-  :ref:`Uploaders <s-f-Uploaders>`

-  :ref:`Section <s-f-Section>` (recommended)

-  :ref:`Priority <s-f-Priority>` (recommended)

-  :ref:`Build-Depends et al <s-sourcebinarydeps>`

-  :ref:`Standards-Version <s-f-Standards-Version>` (mandatory)

-  :ref:`Homepage <s-f-Homepage>`

-  :ref:`Version Control System (VCS) fields <s-f-VCS-fields>`

-  :ref:`Testsuite <s-f-Testsuite>`

-  :ref:`Rules-Requires-Root <s-f-Rules-Requires-Root>`

The fields in the binary package stanzas are:

-  :ref:`Package <s-f-Package>` (mandatory)

-  :ref:`Architecture <s-f-Architecture>` (mandatory)

-  :ref:`Section <s-f-Section>` (recommended)

-  :ref:`Priority <s-f-Priority>` (recommended)

-  :ref:`Essential <s-f-Essential>`

-  :ref:`Depends et al <s-binarydeps>`

-  :ref:`Description <s-f-Description>` (mandatory)

-  :ref:`Homepage <s-f-Homepage>`

-  :ref:`Built-Using <s-built-using>`

-  :ref:`Package-Type <s-f-Package-Type>`

The syntax and semantics of the fields are described below.

These fields are used by ``dpkg-gencontrol`` to generate control files
for binary packages (see below), by ``dpkg-genchanges`` to generate the
``.changes`` file to accompany the upload, and by ``dpkg-source`` when
it creates the ``.dsc`` source control file as part of a source archive.
Some fields are folded in ``debian/control``, but not in any other
control file. These tools are responsible for removing the line breaks
from such fields when using fields from ``debian/control`` to generate
other control files. They are also responsible for discarding empty
fields.

The fields here may contain variable references - their values will be
substituted by ``dpkg-gencontrol``, ``dpkg-genchanges`` or
``dpkg-source`` when they generate output control files. See
:ref:`s-substvars` for details.

.. _s-binarycontrolfiles:

Debian binary package control files -- ``DEBIAN/control``
---------------------------------------------------------

The ``DEBIAN/control`` file contains the most vital (and
version-dependent) information about a binary package. It consists of a
single stanza.

The fields in this file are:

-  :ref:`Package <s-f-Package>` (mandatory)

-  :ref:`Source <s-f-Source>`

-  :ref:`Version <s-f-Version>` (mandatory)

-  :ref:`Section <s-f-Section>` (recommended)

-  :ref:`Priority <s-f-Priority>` (recommended)

-  :ref:`Architecture <s-f-Architecture>` (mandatory)

-  :ref:`Essential <s-f-Essential>`

-  :ref:`Depends et al <s-binarydeps>`

-  :ref:`Installed-Size <s-f-Installed-Size>`

-  :ref:`Maintainer <s-f-Maintainer>` (mandatory)

-  :ref:`Description <s-f-Description>` (mandatory)

-  :ref:`Homepage <s-f-Homepage>`

-  :ref:`Built-Using <s-built-using>`

.. _s-debiansourcecontrolfiles:

Debian source package control files -- ``.dsc``
-----------------------------------------------

This file consists of a single stanza, possibly surrounded by an OpenPGP
signature. The fields of that stanza are listed below. Their syntax
is described above, in :ref:`s-controlsyntax`.

-  :ref:`Format <s-f-Format>` (mandatory)

-  :ref:`Source <s-f-Source>` (mandatory)

-  :ref:`Binary <s-f-Binary>`

-  :ref:`Architecture <s-f-Architecture>`

-  :ref:`Version <s-f-Version>` (mandatory)

-  :ref:`Maintainer <s-f-Maintainer>` (mandatory)

-  :ref:`Uploaders <s-f-Uploaders>`

-  :ref:`Homepage <s-f-Homepage>`

-  :ref:`Version Control System (VCS) fields <s-f-VCS-fields>`

-  :ref:`Testsuite <s-f-Testsuite>`

-  :ref:`Dgit <s-f-Dgit>`

-  :ref:`Standards-Version <s-f-Standards-Version>` (mandatory)

-  :ref:`Build-Depends et al <s-sourcebinarydeps>`

-  :ref:`Package-List <s-f-Package-List>` (recommended)

-  :ref:`Checksums-Sha1 and Checksums-Sha256 <s-f-Checksums>`
   (mandatory)

-  :ref:`Files <s-f-Files>` (mandatory)

The Debian source package control file is generated by ``dpkg-source`` when it
builds the source archive, from other files in the source package,
described above. When unpacking, it is checked against the files and
directories in the other parts of the source package.

.. _s-debianchangesfiles:

Debian upload changes control files -- ``.changes``
---------------------------------------------------

The ``.changes`` files are used by the Debian archive maintenance
software to process updates to packages. They consist of a single
stanza, possibly surrounded by an OpenPGP signature. That stanza
contains information from the ``debian/control`` file and other data
about the source package gathered via ``debian/changelog`` and
``debian/rules``.

``.changes`` files have a format version that is incremented whenever
the documented fields or their meaning change. This document describes
format 1.8.

The fields in this file are:

-  :ref:`Format <s-f-Format>` (mandatory)

-  :ref:`Date <s-f-Date>` (mandatory)

-  :ref:`Source <s-f-Source>` (mandatory)

-  :ref:`Binary <s-f-Binary>` (mandatory)

-  :ref:`Architecture <s-f-Architecture>` (mandatory)

-  :ref:`Version <s-f-Version>` (mandatory)

-  :ref:`Distribution <s-f-Distribution>` (mandatory)

-  :ref:`Urgency <s-f-Urgency>` (recommended)

-  :ref:`Maintainer <s-f-Maintainer>` (mandatory)

-  :ref:`Changed-By <s-f-Changed-By>`

-  :ref:`Description <s-f-Description>` (mandatory)

-  :ref:`Closes <s-f-Closes>`

-  :ref:`Changes <s-f-Changes>` (mandatory)

-  :ref:`Checksums-Sha1 and Checksums-Sha256 <s-f-Checksums>`
   (mandatory)

-  :ref:`Files <s-f-Files>` (mandatory)

.. _s-controlfieldslist:

List of fields
--------------

.. _s-f-Source:

``Source``
~~~~~~~~~~

This field identifies the source package name.

In ``debian/control`` or a ``.dsc`` file, this field must contain only
the name of the source package.

In a binary package control file or a ``.changes`` file, the source
package name may be followed by a version number in parentheses.  [#]_
This version number may be omitted (and is, by ``dpkg-gencontrol``) if
it has the same value as the ``Version`` field of the binary package in
question. The field itself may be omitted from a binary package control
file when the source package has the same name and version as the binary
package.

Package names (both source and binary, see
:ref:`s-f-Package`) must consist only of lower case
letters (``a-z``), digits (``0-9``), plus (``+``) and minus (``-``)
signs, and periods (``.``). They must be at least two characters long
and must start with an alphanumeric character.

.. _s-f-Maintainer:

``Maintainer``
~~~~~~~~~~~~~~

The package maintainer's name and email address. The name must come
first, then the email address inside angle brackets ``<>`` (in RFC822
format).

If the maintainer's name contains a full stop then the whole field will
not work directly as an email address due to a misfeature in the syntax
specified in RFC822; a program using this field as an address must check
for this and correct the problem if necessary (for example by putting
the name in round brackets and moving it to the end, and bringing the
email address forward).

See :ref:`s-maintainer` for additional requirements and
information about package maintainers.

.. _s-f-Uploaders:

``Uploaders``
~~~~~~~~~~~~~

List of the names and email addresses of co-maintainers of the package,
if any. If the package has other maintainers besides the one named in
the :ref:`Maintainer field <s-f-Maintainer>`, their names and email
addresses should be listed here. The format of each entry is the same as
that of the Maintainer field, and multiple entries must be comma
separated.

This is normally an optional field, but if the ``Maintainer`` control
field names a group of people and a shared email address, the
``Uploaders`` field must be present and must contain at least one human
with their personal email address.

The Uploaders field in ``debian/control`` can be folded.

.. _s-f-Changed-By:

``Changed-By``
~~~~~~~~~~~~~~

The name and email address of the person who prepared this version of
the package, usually a maintainer. The syntax is the same as for the
:ref:`Maintainer field <s-f-Maintainer>`.

.. _s-f-Section:

``Section``
~~~~~~~~~~~

This field specifies an application area into which the package has been
classified. See :ref:`s-subsections`.

When it appears in the ``debian/control`` file, it gives the value for
the subfield of the same name in the ``Files`` field of the ``.changes``
file. It also gives the default for the same field in the binary
packages.

.. _s-f-Priority:

``Priority``
~~~~~~~~~~~~

This field represents how important it is that the user have the package
installed. See :ref:`s-priorities`.

When it appears in the ``debian/control`` file, it gives the value for
the subfield of the same name in the ``Files`` field of the ``.changes``
file. It also gives the default for the same field in the binary
packages.

.. _s-f-Package:

``Package``
~~~~~~~~~~~

The name of the binary package.

Binary package names must follow the same syntax and restrictions as
source package names. See :ref:`s-f-Source` for the
details.

.. _s-f-Architecture:

``Architecture``
~~~~~~~~~~~~~~~~

Depending on context and the control file used, the ``Architecture``
field can include the following sets of values:

-  A unique single word identifying a Debian machine architecture as
   described in :ref:`s-arch-spec`.

-  An architecture wildcard identifying a set of Debian machine
   architectures, see :ref:`s-arch-wildcard-spec`.
   ``any`` matches all Debian machine architectures and is the most
   frequently used.

-  ``all``, which indicates an architecture-independent package.

-  ``source``, which indicates a source package.

In the main ``debian/control`` file in the source package, this field
may contain the special value ``all``, the special architecture wildcard
``any``, or a list of specific and wildcard architectures separated by
spaces. If ``all`` or ``any`` appears, that value must be the entire
contents of the field. Most packages will use either ``all`` or ``any``.

Specifying a specific list of architectures indicates that the source
will build an architecture-dependent package only on architectures
included in the list. Specifying a list of architecture wildcards
indicates that the source will build an architecture-dependent package
on only those architectures that match any of the specified architecture
wildcards. Specifying a list of architectures or architecture wildcards
other than ``any`` is for the minority of cases where a program is not
portable or is not useful on some architectures. Where possible, the
program should be made portable instead.

In the Debian source package control file ``.dsc``, this field contains a list
of architectures and architecture wildcards separated by spaces. When
the list contains the architecture wildcard ``any``, the only other
value allowed in the list is ``all``.

The list may include (or consist solely of) the special value ``all``.
In other words, in ``.dsc`` files unlike the ``debian/control``, ``all``
may occur in combination with specific architectures. The
``Architecture`` field in the Debian source package control file ``.dsc`` is
generally constructed from the ``Architecture`` fields in the
``debian/control`` in the source package.

Specifying only ``any`` indicates that the source package isn't
dependent on any particular architecture and should compile fine on any
one. The produced binary package(s) will be specific to whatever the
current build architecture is.

Specifying only ``all`` indicates that the source package will only
build architecture-independent packages.

Specifying ``any all`` indicates that the source package isn't dependent
on any particular architecture. The set of produced binary packages will
include at least one architecture-dependent package and one
architecture-independent package.

Specifying a list of architectures or architecture wildcards indicates
that the source will build an architecture-dependent package, and will
only work correctly on the listed or matching architectures. If the
source package also builds at least one architecture-independent
package, ``all`` will also be included in the list.

In a ``.changes`` file, the ``Architecture`` field lists the
architecture(s) of the package(s) currently being uploaded. This will be
a list; if the source for the package is also being uploaded, the
special entry ``source`` is also present. ``all`` will be present if any
architecture-independent packages are being uploaded. Architecture
wildcards such as ``any`` must never occur in the ``Architecture`` field
in the ``.changes`` file.

See :ref:`s-debianrules` for information on how to get
the architecture for the build process.

.. _s-f-Essential:

``Essential``
~~~~~~~~~~~~~

This is a boolean field which may occur only in the control file of a
binary package or in a binary package stanza of a source package
template control file.

If set to ``yes`` then the package management system will refuse to
remove the package (upgrading and replacing it is still possible). The
other possible value is ``no``, which is the same as not having the
field at all.

.. _s5.6.10:

Package interrelationship fields: ``Depends``, ``Pre-Depends``, ``Recommends``, ``Suggests``, ``Breaks``, ``Conflicts``, ``Provides``, ``Replaces``, ``Enhances``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

These fields describe the package's relationships with other packages.
Their syntax and semantics are described in
:doc:`Declaring relationships between packages <ch-relationships>`.

.. _s-f-Standards-Version:

``Standards-Version``
~~~~~~~~~~~~~~~~~~~~~

The most recent version of the standards (the policy manual and
associated texts) with which the package complies.  See
:ref:`s-standardsversion`.

The version number has four components: major and minor version number
and major and minor patch level. When the standards change in a way that
requires every package to change the major number will be changed.
Significant changes that will require work in many packages will be
signaled by a change to the minor number. The major patch level will be
changed for any change to the meaning of the standards, however small;
the minor patch level will be changed when only cosmetic, typographical
or other edits are made which neither change the meaning of the document
nor affect the contents of packages.

Thus only the first three components of the policy version are
significant in the *Standards-Version* control field, and so either
these three components or all four components may be specified. [#]_

udebs and source packages that only produce udebs do not use
``Standards-Version``.

.. _s-f-Version:

``Version``
~~~~~~~~~~~

The version number of a package. The format is:
``[epoch:]upstream_version[-debian_revision]``.

The three components here are:

``epoch``
    This is a single (generally small) unsigned integer. It may be
    omitted, in which case zero is assumed.

    Epochs can help when the upstream version numbering scheme
    changes, but they must be used with care.  You should not change
    the epoch, even in experimental, without getting consensus on
    debian-devel first.

``upstream_version``
    This is the main part of the version number. It is usually the
    version number of the original ("upstream") package from which the
    ``.deb`` file has been made, if this is applicable. Usually this
    will be in the same format as that specified by the upstream
    author(s); however, it may need to be reformatted to fit into the
    package management system's format and comparison scheme.

    The comparison behavior of the package management system with
    respect to the ``upstream_version`` is described below. The
    ``upstream_version`` portion of the version number is mandatory.

    The ``upstream_version`` must contain only alphanumerics [#]_ and
    the characters ``.`` ``+`` ``-`` ``~`` (full stop, plus, hyphen,
    tilde) and should start with a digit. If there is no
    ``debian_revision`` then hyphens are not allowed.

``debian_revision``
    This part of the version number specifies the version of the Debian
    package based on the upstream version. It must contain only
    alphanumerics and the characters ``+`` ``.`` ``~`` (plus, full stop,
    tilde) and is compared in the same way as the ``upstream_version`` is.

    It is conventional to restart the ``debian_revision`` at ``1`` each
    time the ``upstream_version`` is increased.

    The package management system will break the version number apart at
    the last hyphen in the string (if there is one) to determine the
    ``upstream_version`` and ``debian_revision``. The absence of a
    ``debian_revision`` is equivalent to a ``debian_revision`` of ``0``.

    Presence of the ``debian_revision`` part indicates this package is a
    non-native package (see :ref:`s-source-packages`).  Absence indicates
    the package is a native package.

When comparing two version numbers, first the epoch of each are
compared, then the ``upstream_version`` if epoch is equal, and then
``debian_revision`` if ``upstream_version`` is also equal. epoch is compared
numerically. The ``upstream_version`` and ``debian_revision`` parts are
compared by the package management system using the following algorithm:

The strings are compared from left to right.

First the initial part of each string consisting entirely of non-digit
characters is determined. These two parts (one of which may be empty)
are compared lexically. If a difference is found it is returned. The
lexical comparison is a comparison of ASCII values modified so that all
the letters sort earlier than all the non-letters and so that a tilde
sorts before anything, even the end of a part. For example, the
following parts are in sorted order from earliest to latest: ``~~``,
``~~a``, ``~``, the empty part, ``a``. [#]_

Then the initial part of the remainder of each string which consists
entirely of digit characters is determined. The numerical values of
these two parts are compared, and any difference found is returned as
the result of the comparison. For these purposes an empty string (which
can only occur at the end of one or both version strings being compared)
counts as zero.

These two steps (comparing and removing initial non-digit strings and
initial digit strings) are repeated until a difference is found or both
strings are exhausted.

.. _s-avoid-epochs:

Epochs should be used sparingly
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Note that the purpose of epochs is to cope with situations where the
upstream version numbering scheme changes and to allow us to leave
behind serious mistakes.
If you think that increasing the epoch is the right solution,
you should consult debian-devel and get consensus before doing so
(even in experimental).

Epochs should not be used when a package needs to be rolled back.
In that case, use the ``+really`` convention: for example, if you
uploaded ``2.3-3`` and now you need to go backwards to upstream 2.2,
call your reverting upload something like ``2.3+really2.2-1``.
Eventually, when we upload upstream 2.4, the ``+really`` part can go away.

Epochs are also not intended to cope with version
numbers containing strings of letters which the package management
system cannot interpret (such as ``ALPHA`` or ``pre-``), or with silly
orderings.  [#]_

Special version conventions
^^^^^^^^^^^^^^^^^^^^^^^^^^^

The following special version numbering conventions are used in the Debian
archive:

- The absence of ``debian_revision``, and therefore of a hyphen in the
  version number, indicates that the package is native.

- The presence of ``+really`` in the ``upstream_version`` component
  indicates that a newer upstream version has been rolled back to an older
  upstream version.  The part of the ``upstream_version`` component
  following ``+really`` is the true upstream version.  See
  :ref:`s-avoid-epochs` for an example of when this is used.

Non-maintainer uploads:

- ``debian_revision`` components ending in ``.`` (period) followed by a number
  indicate this version of the non-native package was uploaded by someone
  other than the maintainer (an NMU or non-maintainer upload).  This is used
  for a upload including a source package; for uploads of only binary packages
  without source changes, see the binary NMU convention below.

- ``upstream_version`` components in native packages ending in ``+nmu``
  followed by a number indicate an NMU of a native package.  As with the
  convention for non-native packages, this is used for an upload including a
  source package, not for uploads of only binary packages without source
  changes.

- ``upstream_version`` components in native packages or
  ``debian_revision`` components in non-native packages ending in ``+b``
  followed by a number indicate a binary NMU: an upload of a binary
  package without any source changes and hence without any corresponding
  source package upload or version change.

Stable updates:

- ``debian_revision`` components in non-native packages ending in ``debNuX``
  also indicate a stable update.  Either ``~`` or ``+`` will be used before
  this string depending on the details of the update.  ``N`` is the major
  version number of the Debian stable release to which the package was
  uploaded, and ``X`` is a number, starting at 1, that is increased for each
  stable upload of this package.

  There are three cases for non-native packages:

  #. For stable updates that use the same upstream version, the
     ``debian_revision`` component will end in ``+debNuX``.  The portion
     of the version before that string is the original package version in
     the stable release.

  #. For stable updates to a new upstream version that is based on a newer
     unstable package, the ``debian_revision`` component will end in
     ``~debNuX``.  The portion before that string will be the unstable
     version on which the package is based.

  #. If a stable update is based on a new upstream version but is not
     based on a newer unstable package, the convention is to form the
     version number by taking the upstream version, appending ``-0``, and
     then appending ``+debNuX`` (so the ``debian_revision`` component will
     be ``0+debNuX``).

  In all cases, these versions are chosen so that they will sort earlier
  than a subsequent unstable package of the same upstream version and thus
  that the stable package will upgrade to a newer version during a
  subsequent system upgrade.

  For example, suppose Debian 10 released with a package with version
  ``1.4-5``.  If that package later receives a stable update in Debian 10
  that uses the same upstream version, the first update would have the
  version ``1.4-5+deb10u1``.  A subsequent update would have version
  ``1.4-5+deb10u2``.

  If instead the package receives a stable update based on a ``1.5-1``
  unstable package, the first such stable update would have the version
  ``1.5-1~deb10u1`` and a subsequent update would have the version
  ``1.5-1~deb10u2``.

  If there were no unstable ``1.5-1`` package, but there were a stable
  update to an upstream 1.5 release, the first such stable update would
  have the version ``1.5-0+deb10u1``.

- ``upstream_version`` components in native packages ending in ``+debNuX``
  indicate a stable update.  This is a version of the package uploaded
  directly to a stable release, and the version is chosen to sort before any
  later version of the package uploaded to Debian's unstable or a later stable
  distribution.  As with non-native packages, ``N`` is the major version
  number of the Debian stable release to which the package was uploaded, and
  ``X`` is a number, starting at 1, that is increased for each stable upload
  of this package.

  For example, suppose Debian 10 released with a package with version
  ``1.4``.  The first stable update of that package would have the version
  ``1.4+deb10u1``, and a subsequent update would have the version
  ``1.4+deb10u2``.  These versions are chosen to sort before ``1.5`` (the
  next unstable version) or ``1.4+deb11u1`` (a stable update to a
  subsequent Debian 11 release).

Backports:

- ``upstream_version`` components in native packages or
  ``debian_revision`` components in non-native packages ending in
  ``~bpoNuX`` indicate a backport of a version of the package to an older
  stable release.  The part of the version before ``~bpo`` is the version
  of the package being backported, ``N`` is the major version number of
  the Debian stable release to which the package was backported, and ``X``
  is a number, starting at 1, that is increased for each revision of the
  backport of that package version.  The rationale is the same as for
  stable updates, with the additional goal of ensuring a backported
  version sorts earlier than a stable update with the same upstream
  version.

  Be aware that the stable update and backport conventions can stack.  If,
  for example, Debian 10 contains a package with version ``1.4-5+deb10u1``
  and that package is backported to Debian 9, the version of the Debian 9
  backport would be ``1.4-5+deb10u1~bpo9u1`` (although this scenario is
  rare).

This list of version conventions is not exhaustive.

.. _s-f-Description:

``Description``
~~~~~~~~~~~~~~~

In a source template control file or binary control file, the ``Description``
field contains a description of the binary package, consisting of two parts,
the synopsis or the short description, and the long description. It is a
multiline field with the following format:

.. code-block:: debcontrol

    Description: single line synopsis
     extended description over several lines

The lines in the extended description can have these formats:

-  Those starting with a single space are part of a paragraph.
   Successive lines of this form will be word-wrapped when displayed.
   The leading space will usually be stripped off. The line must contain
   at least one non-whitespace character.

-  Those starting with two or more spaces. These will be displayed
   verbatim. If the display cannot be panned horizontally, the
   displaying program will line wrap them "hard" (i.e., without taking
   account of word breaks). If it can they will be allowed to trail off
   to the right. None, one or two initial spaces may be deleted, but the
   number of spaces deleted from each line will be the same (so that you
   can have indenting work correctly, for example). The line must
   contain at least one non-whitespace character.

-  Those containing a single space followed by a single full stop
   character. These are rendered as blank lines. This is the *only* way
   to get a blank line.  [#]_

-  Those containing a space, a full stop and some more characters. These
   are for future expansion. Do not use them.

Do not use tab characters. Their effect is not predictable.

See :ref:`s-descriptions` for further information on
this.

In a ``.changes`` file, the ``Description`` field contains a summary of
the descriptions for the packages being uploaded. For this case, the
first line of the field value (the part on the same line as
``Description:``) is always empty. It is a multiline field, with one
line per package. Each line is indented by one space and contains the
name of a binary package, a space, a hyphen (``-``), a space, and the
short description line from that package.

.. _s-f-Distribution:

``Distribution``
~~~~~~~~~~~~~~~~

In a ``.changes`` file or parsed changelog output this contains the
(space-separated) name(s) of the distribution(s) where this version of
the package should be installed. Valid distributions are determined by
the archive maintainers.  [#]_ The Debian archive software only
supports listing a single distribution. Migration of packages to other
distributions is handled outside of the upload process.

.. _s-f-Date:

``Date``
~~~~~~~~

This field includes the date the package was built or last edited. It
must be in the same format as the date in a ``debian/changelog`` entry.

The value of this field is usually extracted from the
``debian/changelog`` file - see :ref:`s-dpkgchangelog`).

.. _s-f-Format:

``Format``
~~~~~~~~~~

In |changes link|_ files, this field declares the format version of
that file. The syntax of the field value is the same as that of a
:ref:`package version number <s-f-Version>` except that no epoch or
Debian revision is allowed. The format described in this document is
1.8.

In |dsc link|_ files, this field declares the format of the source
package. The field value is used by programs acting on a source
package to interpret the list of files in the source package and
determine how to unpack it. The syntax of the field value is a numeric
major revision, a period, a numeric minor revision, and then an
optional subtype after whitespace, which if specified is an
alphanumeric word in parentheses. The subtype is optional in the
syntax but may be mandatory for particular source format revisions.
[#]_

.. |changes link| replace:: ``.changes``
.. _changes link: #s-debianchangesfiles
.. |dsc link| replace:: ``.dsc`` Debian source control
.. _dsc link: #s-debiansourcecontrolfiles

.. _s-f-Urgency:

``Urgency``
~~~~~~~~~~~

This is a description of how important it is to upgrade to this version
from previous ones. It consists of a single keyword taking one of the
values ``low``, ``medium``, ``high``, ``emergency``, or ``critical``
[#]_ (not case-sensitive) followed by an optional commentary
(separated by a space) which is usually in parentheses. For example:

.. code-block:: debcontrol

    Urgency: low (HIGH for users of diversions)

The value of this field is usually extracted from the
``debian/changelog`` file - see :ref:`s-dpkgchangelog`.

.. _s-f-Changes:

``Changes``
~~~~~~~~~~~

This multiline field contains the human-readable changes data,
describing the differences between the last version and the current one.

The first line of the field value (the part on the same line as
``Changes:``) is always empty. The content of the field is expressed as
continuation lines, with each line indented by at least one space. Blank
lines must be represented by a line consisting only of a space and a
full stop (``.``).

The value of this field is usually extracted from the
``debian/changelog`` file - see :ref:`s-dpkgchangelog`.

Each version's change information should be preceded by a "title" line
giving at least the version, distribution(s) and urgency, in a
human-readable way.

If data from several versions is being returned the entry for the most
recent version should be returned first, and entries should be separated
by the representation of a blank line (the "title" line may also be
followed by the representation of a blank line).

.. _s-f-Binary:

``Binary``
~~~~~~~~~~

This folded field is a list of binary packages. Its syntax and meaning
varies depending on the control file in which it appears.

When it appears in the ``.dsc`` file, it lists binary packages which a
source package can produce, separated by commas [#]_. The source
package does not necessarily produce all of these binary packages for
every architecture. The source control file doesn't contain details of
which architectures are appropriate for which of the binary packages.

When it appears in a ``.changes`` file, it lists the names of the binary
packages being uploaded, separated by whitespace (not commas).

.. _s-f-Installed-Size:

``Installed-Size``
~~~~~~~~~~~~~~~~~~

This field appears in the binary package control files, and in the
``Packages`` files. It gives an estimate of the total amount of disk
space required to install the named package. Actual installed size may
vary based on block size, file system properties, or actions taken by
package maintainer scripts.

The disk space is given as the accumulated size of each regular file and
symlink rounded to 1 KiB used units, and a baseline of 1 KiB for any other
filesystem object type.

.. _s-f-Files:

``Files``
~~~~~~~~~

This field contains a list of files with information about each one. The
exact information and syntax varies with the context.

In all cases, ``Files`` is a multiline field. The first line of the field
value (the part on the same line as ``Files:``) is always empty. The
content of the field is expressed as continuation lines, one line per
file. Each line must be indented by one space and contain a number of
sub-fields, separated by spaces, as described below.

In the ``.dsc`` file, each line contains the MD5 checksum, size and
filename of the tar file and (if applicable) diff file which make up the
remainder of the source package.  [#]_ For example:

::

    Files:
     c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
     938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz

The exact forms of the filenames are described in
:ref:`s-pkg-sourcearchives`.

In the ``.changes`` file this contains one line per file being uploaded.
Each line contains the MD5 checksum, size, section and priority and the
filename. For example:

::

    Files:
     4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
     c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
     938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
     7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb

The :ref:`section <s-f-Section>` and :ref:`priority <s-f-Priority>` are the
values of the corresponding fields in the source template control file. If
no section or priority is specified then ``-`` should be used, though
section and priority values must be specified for new packages to be
installed properly.

The special value ``byhand`` for the section in a ``.changes`` file
indicates that the file in question is not an ordinary package file and
must be installed by hand by the distribution maintainers. If the
section is ``byhand`` the priority should be ``-``.

If a new Debian revision of a package is being shipped and no new
original source archive is being distributed the ``.dsc`` must still
contain the ``Files`` field entry for the original source archive
``package_upstream-version.orig.tar.gz``, but the ``.changes`` file
should leave it out. In this case the original source archive on the
distribution site must match exactly, byte-for-byte, the original source
archive which was used to generate the ``.dsc`` file and diff which are
being uploaded.

.. _s-f-Closes:

``Closes``
~~~~~~~~~~

A space-separated list of bug report numbers that the upload governed by
the ``.changes`` file closes.

.. _s-f-Homepage:

``Homepage``
~~~~~~~~~~~~

The URL of the web site for this package, preferably (when applicable)
the site from which the original source can be obtained and any
additional upstream documentation or information may be found. The
content of this field is a simple URL without any surrounding characters
such as ``<>``.

.. _s-f-Checksums:

``Checksums-Sha1`` and ``Checksums-Sha256``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

These multiline fields contain a list of files with a checksum and size
for each one. Both ``Checksums-Sha1`` and ``Checksums-Sha256`` have the
same syntax and differ only in the checksum algorithm used: SHA-1 for
``Checksums-Sha1`` and SHA-256 for ``Checksums-Sha256``.

``Checksums-Sha1`` and ``Checksums-Sha256`` are multiline fields. The
first line of the field value (the part on the same line as
``Checksums-Sha1:`` or ``Checksums-Sha256:``) is always empty. The
content of the field is expressed as continuation lines, one line per
file. Each line consists of the checksum, a space, the file size, a
space, and the file name. For example (from a ``.changes`` file):

::

    Checksums-Sha1:
     1f418afaa01464e63cc1ee8a66a05f0848bd155c 1276 example_1.0-1.dsc
     a0ed1456fad61116f868b1855530dbe948e20f06 171602 example_1.0.orig.tar.gz
     5e86ecf0671e113b63388dac81dd8d00e00ef298 6137 example_1.0-1.debian.tar.gz
     71a0ff7da0faaf608481195f9cf30974b142c183 548402 example_1.0-1_i386.deb
    Checksums-Sha256:
     ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272 1276 example_1.0-1.dsc
     0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128 171602 example_1.0.orig.tar.gz
     f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288 6137 example_1.0-1.debian.tar.gz
     3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664 548402 example_1.0-1_i386.deb

In the ``.dsc`` file, these fields list all files that make up the
source package. In the ``.changes`` file, these fields list all files
being uploaded. The list of files in these fields must match the list of
files in the ``Files`` field.

.. _s5.6.25:

``DM-Upload-Allowed``
~~~~~~~~~~~~~~~~~~~~~

Obsolete, see :ref:`below <s-f-DM-Upload-Allowed>`.

.. _s-f-VCS-fields:

Version Control System (VCS) fields
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Debian source packages are increasingly developed using VCSs. The
purpose of the following fields is to indicate a publicly accessible
repository where the Debian source package is developed.

``Vcs-Browser``
    URL of a web interface for browsing the repository.

``Vcs-<type>``
    The field name identifies the VCS. The field's value uses the version
    control system's conventional syntax for describing repository
    locations and should be sufficient to locate the repository used for
    packaging. Ideally, it also locates the branch used for development of
    new versions of the Debian package.

    The following values for <type> are supported, with the corresponding
    VCS indicated in parentheses if it isn't obvious:

    - Arch
    - Bzr (Bazaar)
    - Cvs (CVS)
    - Darcs
    - Git
    - Hg (Mercurial)
    - Mtn (Monotone)
    - Svn (Subversion)

    In the case of Git, the value must have the following syntax::

        <url> [ " -b " <branch> ] [ " [" <path> "]" ]

    where the portions enclosed in brackets are optional and the portions
    enclosed in double quotes are literal strings.  ``<url>`` indicates
    the repository.  If the ``<branch>`` portion is present, it names a
    branch in the indicated repository.  If no branch is specified, the
    packaging should be on the default branch.  If the ``<path>`` portion
    is present, it specifies the relative path to the top of the packaging
    tree (the parent directory of the ``debian`` directory).  If no path
    is specified, it defaults to ``.`` (the top level of the indicated
    repository and branch).

    For example:

    .. code-block:: debcontrol

        Vcs-Git: https://example.org/repo -b debian [p/package]

    indicates a subdirectory named ``p/package`` in the ``debian`` branch
    of the repository at ``https://example.org/repo``.

    In the case of Mercurial, the value must have the following syntax::

        <url> [ " -b " <branch> ]

    This is interpreted the same way as the Git syntax except a path
    within the repository is not supported.

    A package control file must not have more than one ``Vcs-<type>``
    field.  If the package is maintained in multiple version control
    systems, the maintainer should specify the one that they would
    prefer other people to use as the basis for proposing changes to
    the package.

For both fields, any URLs given should use a scheme that provides
confidentiality (``https``, for example, rather than ``http`` or ``git``)
if the VCS repository supports it.

.. _s-f-Package-List:

``Package-List``
~~~~~~~~~~~~~~~~

Multiline field listing all the packages that can be built from the
source package, considering every architecture. The first line of the
field value is empty. Each one of the next lines describes one binary
package, by listing its name, type, section and priority separated by
spaces. Fifth and subsequent space-separated items may be present and
parsers must allow them. See the :ref:`Package-Type <s-f-Package-Type>`
field for a list of package types.

.. _s-f-Package-Type:

``Package-Type``
~~~~~~~~~~~~~~~~

Simple field containing a word indicating the type of package: ``deb``
for binary packages and ``udeb`` for micro binary packages. Other types
not defined here may be indicated. In source package template control files,
the ``Package-Type`` field should be omitted instead of giving it a value of
``deb``, as this value is assumed for stanzas lacking this field.

.. _s-f-Dgit:

``Dgit``
~~~~~~~~

Folded field containing a single git commit hash, presented in full,
followed optionally by whitespace and other data to be defined in future
extensions.

Declares that the source package corresponds exactly to a referenced
commit in a Git repository available at the canonical location called
*dgit-repos*, used by ``dgit``, a bidirectional gateway between the
Debian archive and Git. The commit is reachable from at least one
reference whose name matches ``refs/dgit/*``. See the manual page of
``dgit`` for further details.

.. _s-f-Testsuite:

``Testsuite``
~~~~~~~~~~~~~

Simple field containing a comma-separated list of values allowing test
execution environments to discover packages which provide tests.

This field is automatically added to Debian source control files
(``.dsc``) by ``dpkg``, with the value ``autopkgtest``, when a
``debian/tests/control`` file is present in the source package. This
field may also be used in source package template control files
(``debian/control``) if needed in other situations.

.. _s-f-Rules-Requires-Root:

``Rules-Requires-Root``
~~~~~~~~~~~~~~~~~~~~~~~

Simple field that defines if the source package requires access to
root (or fakeroot) during selected targets in the :ref:`Main building
script: debian/rules <s-debianrules>`.

The field can consist of exactly one of the following three items:

 - ``no``: Declares that neither root nor fakeroot is required.
   Package builders (e.g. dpkg-buildpackage) may choose to invoke any
   target in ``debian/rules`` with an unprivileged user.

 - ``binary-targets`` (default): Declares that the package will need
   the root (or fakeroot) when either of the ``binary``,
   ``binary-arch`` or ``binary-indep`` targets are called.  This is
   how every tool behaved before this field was defined.

 - A space separated list of keywords described below.  These keywords
   must always contain a forward slash, which sets them apart from the
   other possible values of ``Rules-Requires-Root``.  When this list
   is provided, the builder must provide a "gain root command" (as
   defined in :ref:`debian/rules and Rules-Requires-Root
   <s-debianrules-gainrootapi>`) *or* pretend that the value was set
   to ``binary-targets``, and both the builder and the package's
   ``debian/rules`` script must downgrade accordingly (see below).

If the package builder supports the ``Rules-Requires-Root`` field and
wants to enable the feature, then it must set the environment variable
``DEB_RULES_REQUIRES_ROOT`` when invoking the package building script
``debian/rules``.  The value of ``DEB_RULES_REQUIRES_ROOT`` should be
one of:

 * The value of ``Rules-Requires-Root`` if the builder can support
   that value.  The builder may trim unnecessary whitespace used to
   format the field for readability.

 * The value ``binary-targets`` if it cannot support the value of
   ``Rules-Requires-Root``.

A compliant builder may also leave ``DEB_RULES_REQUIRES_ROOT`` unset
or set it to ``binary-targets`` if it has been requested to test
whether the package it builds correctly implements the fall-back for
legacy builders.

Remarks
^^^^^^^

All packages and builders must support ``binary-targets`` as this was
the historical behaviour prior to the introduction of this field.

Any tool (particularly older versions of them) may be unaware of this
field and behave like the field was set to ``binary-targets``.  The
package build must gracefully cope with this and produce a
semantically equivalent result.

This field intentionally does not enable a package to request a true
root over fakeroot.

Definition of the keywords
^^^^^^^^^^^^^^^^^^^^^^^^^^

The keywords have the format ``<namespace>/<case>``, where:

 * ``<namespace>`` must consist entirely of printable ASCII characters
   except for any whitespace and the forward slash (``/``).  It must
   consist of at least 2 characters.

 * ``/`` (between ``<namespace>`` and ``<case>``) is a single ASCII
   forward slash.

 * ``<case>`` must consist entirely of printable ASCII characters
   except for any whitespace.  It must consist of at least 2
   characters.

These keywords define where the package build script ``debian/rules``,
or the tools called by that script, will need access to root or
fakeroot.

In addition to the keywords defined in the next section, each tool or
package may define keywords within a namespace named after that tool
or package.  The package or tool is considered to own that namespace.

A tool is permitted to use the "gain root command" to do something under
(fake)root if and only if the tool defines an appropriate keyword in its
namespace, and the package lists that keyword in ``Rules-Requires-Root``.

All tools must ignore keywords under namespaces they do not know or
own.  A tool may emit a warning, or abort with an error, if it finds
unknown keywords in namespaces it owns, but it is not required to do
this for all keywords in the namespace.

Provided keywords
^^^^^^^^^^^^^^^^^

The following keywords are defined:

 * ``dpkg/target-subcommand``: declares that there exists a command
   that the ``debian/rules`` file must run under (fake)root

 * ``dpkg/target/foo``: declares that the additional, package-specific
   target ``foo`` (that is, not one of the targets specified in
   :ref:`Main building script: debian/rules <s-debianrules>`) must be
   run under (fake)root

This list is intentionally incomplete. You should consult the
documentation of the tool or package in question for which keywords it
defines and when they are needed.

.. _s5.7:

User-defined fields
-------------------

Additional user-defined fields may be added to the source package template
control file. Such fields will be ignored, and not copied to (for
example) binary or Debian source control files or
Debian upload changes control files.

If you wish to add additional unsupported fields to these output files
you should use the mechanism described here.

Fields in the source package template control file with names starting
``X``, followed by one or more of the letters ``BCS`` and a hyphen
``-``, will be copied to the output files. Only the part of the field
name after the hyphen will be used in the output file. Where the letter
``B`` is used the field will appear in binary package control files,
where the letter ``S`` is used in Debian source control files and where
``C`` is used in Debian upload changes control files.

For example, if the source package template control file contains the
field

.. code-block:: debcontrol

    XBS-Comment: I stand between the candle and the star.

then the binary and Debian source control files will contain the field

.. code-block:: debcontrol

    Comment: I stand between the candle and the star.

.. _s-obsolete-control-data-fields:

Obsolete fields
---------------

The following fields have been obsoleted and may be found in packages
conforming with previous versions of the Policy.

.. _s-f-DM-Upload-Allowed:

``DM-Upload-Allowed``
~~~~~~~~~~~~~~~~~~~~~

Indicates that Debian Maintainers may upload this package to the Debian
archive. The only valid value is ``yes``. This field was used to
regulate uploads by Debian Maintainers, See the General Resolution
`Endorse the concept of Debian
Maintainers <https://www.debian.org/vote/2007/vote_003>`_ for more
details.

.. [#]
   ``dpkg``'s internal databases are in a similar format.

.. [#]
   The stanzas somtimes used to be referred to as paragraphs, but that
   caused confusion with text paragraphs in prose, so it is now considered
   a discouraged term.

.. [#]
   This folding method is similar to RFC 5322, allowing control files
   that contain only one stanza and no multiline fields to be read by
   parsers written for RFC 5322.

.. [#]
   It is customary to leave a space after the package name if a version
   number is specified.

.. [#]
   In the past, people specified the full version number in the
   Standards-Version field, for example "2.3.0.0". Since minor
   patch-level changes don't introduce new policy, it was thought it
   would be better to relax policy and only require the first 3
   components to be specified, in this example "2.3.0". All four
   components may still be used if someone wishes to do so.

.. [#]
   Alphanumerics are ``A-Za-z0-9`` only.

.. [#]
   One common use of ``~`` is for upstream pre-releases. For example,
   ``1.0~beta1~svn1245`` sorts earlier than ``1.0~beta1``, which sorts
   earlier than ``1.0``.

.. [#]
   The author of this manual has heard of a package whose versions went
   ``1.1``, ``1.2``, ``1.3``, ``1``, ``2.1``, ``2.2``, ``2`` and so
   forth.

.. [#]
   Completely empty lines will not be rendered as blank lines. Instead,
   they will cause the parser to think you're starting a whole new
   record in the control file, and will therefore likely abort with an
   error.

.. [#]
   Example distribution names in the Debian archive used in ``.changes``
   files are:

   *unstable*
       This distribution value refers to the *developmental* part of the
       Debian distribution tree. Most new packages, new upstream
       versions of packages and bug fixes go into the *unstable*
       directory tree.

   *experimental*
       The packages with this distribution value are deemed by their
       maintainers to be high risk. Oftentimes they represent early beta
       or developmental packages from various sources that the
       maintainers want people to try, but are not ready to be a part of
       the other parts of the Debian distribution tree.

   Others are used for updating stable releases or for security uploads.
   More information is available in the Debian Developer's Reference,
   section "The Debian archive".

.. [#]
   The source formats currently supported by the Debian archive software
   are ``1.0``, ``3.0 (native)``, and ``3.0 (quilt)``.

.. [#]
   Other urgency values are supported with configuration changes in the
   archive software but are not used in Debian. The urgency affects how
   quickly a package will be considered for inclusion into the
   ``testing`` distribution and gives an indication of the importance of
   any fixes included in the upload. ``Emergency`` and ``critical`` are
   treated as synonymous.

.. [#]
   A space after each comma is conventional.

.. [#]
   That is, the parts which are not the ``.dsc``.
