<structfield>udt_catalog</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Name of the database that the data type of the parameter is
       defined in (always the current database)
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>udt_schema</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Name of the schema that the data type of the parameter is
       defined in
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>udt_name</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Name of the data type of the parameter
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>scope_catalog</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Applies to a feature not available in <productname>PostgreSQL</productname>
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>scope_schema</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Applies to a feature not available in <productname>PostgreSQL</productname>
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>scope_name</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Applies to a feature not available in <productname>PostgreSQL</productname>
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>maximum_cardinality</structfield> <type>cardinal_number</type>
      </para>
      <para>
       Always null, because arrays always have unlimited maximum cardinality in <productname>PostgreSQL</productname>
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>dtd_identifier</structfield> <type>sql_identifier</type>
      </para>
      <para>
       An identifier of the data type descriptor of the parameter,
       unique among the data type descriptors pertaining to the
       function.  This is mainly useful for joining with other
       instances of such identifiers.  (The specific format of the
       identifier is not defined and not guaranteed to remain the same
       in future versions.)
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>parameter_default</structfield> <type>character_data</type>
      </para>
      <para>
       The default expression of the parameter, or null if none or if the
       function is not owned by a currently enabled role.
      </para></entry>
     </row>
    </tbody>
   </tgroup>
  </table>
 </sect1>

 <sect1 id="infoschema-referential-constraints">
  <title><literal>referential_constraints</literal></title>

  <para>
   The view <literal>referential_constraints</literal> contains all
   referential (foreign key) constraints in the current database.
   Only those constraints are shown for which the current user has
   write access to the referencing table (by way of being the
   owner or having some privilege other than <literal>SELECT</literal>).
  </para>

  <table>
   <title><structname>referential_constraints</structname> Columns</title>
   <tgroup cols="1">
    <thead>
     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       Column Type
      </para>
      <para>
       Description
      </para></entry>
     </row>
    </thead>

    <tbody>
     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>constraint_catalog</structfield> <type>sql_identifier</type>