<a class="xref" href="xfunc-sql.html" title="38.5. Query Language (SQL) Functions">Section 38.5</a>)
     </p></li><li class="listitem"><p>
      procedural language functions (functions written in, for
      example, <span class="application">PL/pgSQL</span> or <span class="application">PL/Tcl</span>)
      (<a class="xref" href="xfunc-pl.html" title="38.8. Procedural Language Functions">Section 38.8</a>)
     </p></li><li class="listitem"><p>
      internal functions (<a class="xref" href="xfunc-inter