procedure, then
       the effects of a <command>SET LOCAL</command> command executed inside the
       procedure for the same variable are restricted to the procedure: the
       configuration parameter's prior value is still restored at procedure exit.
       However, an ordinary
       <command>SET</command> command (without <literal>LOCAL</literal>) overrides the
       <literal>SET</literal> clause, much as it would do for a previous <command>SET
       LOCAL</command> command: the effects of such a command will persist after
       procedure exit, unless the current transaction is rolled back.
      </para>

      <para>
       If a <literal>SET</literal> clause is attached to a procedure, then
       that procedure cannot execute transaction control statements (for
       example, <command>COMMIT</command> and <command>ROLLBACK</command>,
       depending on the language).
      </para>

      <para>
       See <xref linkend="sql-set"/> and
       <xref linkend="runtime-config"/>
       for more information about allowed parameter names and values.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><replaceable class="parameter">definition</replaceable></term>

     <listitem>
      <para>
       A string constant defining the procedure; the meaning depends on the
       language.  It can be an internal procedure name, the path to an
       object file, an SQL command, or text in a procedural language.
      </para>

      <para>
       It is often helpful to use dollar quoting (see <xref
       linkend="sql-syntax-dollar-quoting"/>) to write the procedure definition
       string, rather than the normal single quote syntax.  Without dollar
       quoting, any single quotes or backslashes in the procedure definition must
       be escaped by doubling them.
      </para>

     </listitem>
    </varlistentry>

    <varlistentry>
     <term><literal><replaceable class="parameter">obj_file</replaceable>, <replaceable class="parameter">link_symbol</replaceable></literal></term>

     <listitem>
      <para>
       This form of the <literal>AS</literal> clause is used for
       dynamically loadable C language procedures when the procedure name
       in the C language source code is not the same as the name of
       the SQL procedure. The string <replaceable
       class="parameter">obj_file</replaceable> is the name of the shared
       library file containing the compiled C procedure, and is interpreted
       as for the <link linkend="sql-load"><command>LOAD</command></link> command.  The string
       <replaceable class="parameter">link_symbol</replaceable> is the
       procedure's link symbol, that is, the name of the procedure in the C
       language source code.  If the link symbol is omitted, it is assumed
       to be the same as the name of the SQL procedure being defined.
      </para>

      <para>
       When repeated <command>CREATE PROCEDURE</command> calls refer to
       the same object file, the file is only loaded once per session.
       To unload and