"column_definition">
       <code class="structfield">external_name</code> <code class="type">character_data</code>
      </p>
      <p>
       If this function is a C function, then the external name (link
       symbol) of the function; else null.  (This works out to be the
       same value that is shown in
       <code class="literal">routine_definition</code>.)
      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
       <code class="structfield">external_language</code>