<section xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="sec-meta-attributes">
  <title>Meta Attributes</title>
  <para>
    Like Nix packages, NixOS modules can declare meta-attributes to
    provide extra information. Module meta attributes are defined in the
    <literal>meta.nix</literal> special module.
  </para>
  <para>
    <literal>meta</literal> is a top level attribute like
    <literal>options</literal> and <literal>config</literal>. Available
    meta-attributes are <literal>maintainers</literal> and
    <literal>doc</literal>.
  </para>
  <para>
    Each of the meta-attributes must be defined at most once per module
    file.
  </para>
  <programlisting language="bash">
{ config, lib, pkgs, ... }:
{
  options = {
    ...
  };

  config = {
    ...
  };

  meta = {
    maintainers = with lib.maintainers; [ ericsagnes ];
    doc = ./default.xml;
  };
}
</programlisting>
  <itemizedlist>
    <listitem>
      <para>
        <literal>maintainers</literal> contains a list of the module
        maintainers.
      </para>
    </listitem>
    <listitem>
      <para>
        <literal>doc</literal> points to a valid DocBook file containing
        the module documentation. Its contents is automatically added to
        <xref linkend="ch-configuration" />. Changes to a module
        documentation have to be checked to not break building the NixOS
        manual:
      </para>
      <programlisting>
$ nix-build nixos/release.nix -A manual.x86_64-linux
</programlisting>
    </listitem>
  </itemizedlist>
</section>
