<application>PL/Perl</application>, you should ensure that the
      <productname>Perl</productname> installation was built with the
      <literal>usemultiplicity</literal> option enabled (<literal>perl -V</literal>
      will show whether this is the case).
     </para>
    </listitem>

    <listitem>
     <para>
      To build the <application>PL/Python</application> server programming
      language, you need a <productname>Python</productname>
      installation with the header files and
      the <application>sysconfig</application> module.  The minimum
      supported version is <productname>Python</productname> 3.6.8.
     </para>

     <para>
      Since <application>PL/Python</application> will be a shared
      library, the <indexterm><primary>libpython</primary></indexterm>
      <filename>libpython</filename> library must be a shared library
      also on most platforms.  This is not the case in a default
      <productname>Python</productname> installation built from source, but a
      shared library is available in many operating system
      distributions.  <filename>configure</filename> will fail if
      building <application>PL/Python</application> is selected but it cannot
      find a shared <filename>libpython</filename>.  That might mean that you
      either have to install additional packages or rebuild (part of) your
      <productname>Python</productname> installation to provide this shared
      library.  When building from source, run <productname>Python</productname>'s
      configure with the <literal>--enable-shared</literal> flag.
     </para>
    </listitem>

    <listitem>
     <para>
      To build the <application>PL/Tcl</application>
      procedural language, you of course need a <productname>Tcl</productname>
      installation.  The minimum required version is
      <productname>Tcl</productname> 8.4.
     </para>
    </listitem>

    <listitem>
     <para>
      To enable Native Language Support (<acronym>NLS</acronym>), that
      is, the ability to display a program's messages in a language
      other than English, you need an implementation of the
      <application>Gettext</application> <acronym>API</acronym>.  Some operating
      systems have this built-in (e.g., <systemitem
      class="osname">Linux</systemitem>, <systemitem class="osname">NetBSD</systemitem>,
      <systemitem class="osname">Solaris</systemitem>), for other systems you
      can download an add-on package from <ulink
      url="https://www.gnu.org/software/gettext/"></ulink>.
      If you are using the <application>Gettext</application> implementation in
      the <acronym>GNU</acronym> C library, then you will additionally
      need the <productname>GNU Gettext</productname> package for some
      utility programs.  For any of the other implementations you will
      not need it.
     </para>
    </listitem>

    <listitem>
     <para>
      You need <productname>OpenSSL</productname>, if you want to support
      encrypted client connections.  <productname>OpenSSL</productname> is
      also required for random number generation on platforms that do not
      have <filename>/dev/urandom</filename> (except Windows).  The minimum
      required version is 1.1.1.
     </para>
     <para>
      Additionally, <productname>LibreSSL</productname> is supported using the
      <productname>OpenSSL</productname> compatibility layer.  The minimum
      required version is 3.4 (from <systemitem class="osname">OpenBSD</systemitem>
      version 7.0).
     </para>
    </listitem>

    <listitem>
     <para>
      You need <application>MIT Kerberos</application> (for GSSAPI),
      <productname>OpenLDAP</productname>, and/or <application>PAM</application>,
      if you want to support authentication using those services.
     </para>
    </listitem>

    <listitem>
     <para>
      You need <productname>Curl</productname> to build an optional module
      which implements the <link linkend="libpq-oauth">OAuth Device