ADDITIONAL_FLAGS='-Xmx1500m'
</programlisting>
    There is a minimum amount of memory that is required, and to some extent
    more memory appears to make things a bit faster.  On systems with very
    little memory (less than 1 GB), the build will either be very slow due to
    swapping or will not work at all.
   </para>

   <para>
    In its default configuration <productname>FOP</productname> will emit an
    <literal>INFO</literal> message for each page. The log level can be
    changed via <filename>~/.foprc</filename>:
<programlisting>
LOGCHOICE=-Dorg.apache.commons.logging.Log=&zwsp;org.apache.commons.logging.impl.SimpleLog
LOGLEVEL=-Dorg.apache.commons.logging.simplelog.defaultlog=WARN
</programlisting>
   </para>

   <para>
    Other XSL-FO processors can also be used manually, but the automated build
    process only supports FOP.
   </para>
  </sect2>

  <sect2 id="docguide-build-syntax-check">
   <title>Syntax Check</title>

   <para>
    Building the documentation can take very long.  But there is a
    method to just check the correct syntax of the documentation
    files, which only takes a few seconds:
<screen>
<prompt>doc/src/sgml$ </prompt><userinput>make check</userinput>
</screen>
   </para>
  </sect2>
 </sect1>


 <sect1 id="docguide-build-meson">
  <title>Building the Documentation with Meson</title>

   <para>
    To build the documentation using Meson, change to the
    <filename>build</filename> directory before running one of these commands,
    or add <option>-C build</option> to the command.
   </para>

   <para>
    To build just the <acronym>HTML</acronym> version of the documentation:
<screen>
<prompt>build$ </prompt><userinput>ninja html</userinput>
</screen>
    For a list of other documentation targets see
    <xref linkend="targets-meson-documentation"/>.

    The output appears in the
    subdirectory <filename>build/doc/src/sgml</filename>.
   </para>
 </sect1>


 <sect1 id="docguide-authoring">
  <title>Documentation Authoring</title>

   <para>
    The documentation sources are most conveniently modified with an editor
    that has a mode for editing XML, and even more so if it has some awareness
    of XML schema languages so that it can know about
    <productname>DocBook</productname> syntax specifically.
   </para>

   <para>
    Note that for historical reasons the documentation source files are named
    with an extension <filename>.sgml</filename> even though they are now XML
    files.  So you might need to adjust your editor configuration to set the
    correct mode.
   </para>

   <sect2 id="docguide-authoring-emacs">
    <title>Emacs</title>

    <para>
     <productname>nXML Mode</productname>, which ships with
     <productname>Emacs</productname>, is the most common mode for editing
     <acronym>XML</acronym> documents with <productname>Emacs</productname>.
     It will allow you to use <application>Emacs</application> to insert tags
     and check markup consistency, and it supports
     <productname>DocBook</productname> out of the box.  Check the <ulink
     url="https://www.gnu.org/software/emacs/manual/html_mono/nxml-mode.html">
     nXML manual</ulink> for detailed documentation.
    </para>

    <para>
     <filename>src/tools/editors/emacs.samples</filename> contains
     recommended settings for this mode.
    </para>
   </sect2>

 </sect1>


 <sect1 id="docguide-style">
  <title>Style Guide</title>

  <sect2 id="docguide-style-ref-pages">
   <title>Reference Pages</title>

   <para>
    Reference pages should follow a standard layout.  This allows
    users to find the desired information more quickly, and it also
    encourages writers to document all relevant aspects of a command.
    Consistency is not only desired among
    <productname>PostgreSQL</productname> reference pages, but also
    with reference pages provided by the operating system and other
    packages.  Hence the following guidelines have been developed.
    They are for the most part consistent