<parameter>bytesremoved</parameter> <type>bytea</type> )
         <returnvalue>bytea</returnvalue>
        </para>
        <para>
         Removes the longest string containing only bytes appearing in
         <parameter>bytesremoved</parameter> from the end of
         <parameter>bytes</parameter>.
        </para>
        <para>
         <literal>rtrim('\x1234567890'::bytea, '\x9012'::bytea)</literal>
         <returnvalue>\x12345678</returnvalue>
        </para></entry>
       </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <indexterm>
         <primary>substring</primary>
        </indexterm>
        <function>substring</function> ( <parameter>bytes</parameter> <type>bytea</type> <optional> <literal>FROM</literal> <parameter>start</parameter> <type>integer</type> </optional> <optional> <literal>FOR</literal> <parameter>count</parameter> <type>integer</type> </optional> )
        <returnvalue>bytea</returnvalue>
       </para>
       <para>
        Extracts the substring of <parameter>bytes</parameter> starting at
        the <parameter>start</parameter>'th byte if that is specified,
        and stopping after <parameter>count</parameter> bytes if that is
        specified.  Provide at least one of <parameter>start</parameter>
        and <parameter>count</parameter>.
       </para>
       <para>
        <literal>substring('\x1234567890'::bytea from 3 for 2)</literal>
        <returnvalue>\x5678</returnvalue>
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <indexterm>
         <primary>trim</primary>
        </indexterm>
        <function>trim</function> ( <optional> <literal>LEADING</literal> | <literal>TRAILING</literal> | <literal>BOTH</literal> </optional>
        <parameter>bytesremoved</parameter> <type>bytea</type> <literal>FROM</literal>
        <parameter>bytes</parameter> <type>bytea</type> )
        <returnvalue>bytea</returnvalue>
       </para>
       <para>
        Removes the longest string containing only bytes appearing in
        <parameter>bytesremoved</parameter> from the start,
        end, or both ends (<literal>BOTH</literal> is the default)
        of <parameter>bytes</parameter>.
       </para>
       <para>
        <literal>trim('\x9012'::bytea from '\x1234567890'::bytea)</literal>
        <returnvalue>\x345678</returnvalue>
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <function>trim</function> ( <optional> <literal>LEADING</literal> | <literal>TRAILING</literal> | <literal>BOTH</literal> </optional> <optional> <literal>FROM</literal> </optional>
        <parameter>bytes</parameter> <type>bytea</type>,
        <parameter>bytesremoved</parameter> <type>bytea</type> )
        <returnvalue>bytea</returnvalue>
       </para>
       <para>
        This is a non-standard syntax for <function>trim()</function>.
       </para>
       <para>
        <literal>trim(both from '\x1234567890'::bytea, '\x9012'::bytea)</literal>
        <returnvalue>\x345678</returnvalue>
       </para></entry>
      </row>
     </tbody>
    </tgroup>
   </table>

   <para>
    Additional binary string manipulation functions are available and
    are listed in <xref linkend="functions-binarystring-other"/>.  Some
    of them are used internally to implement the
    <acronym>SQL</acronym>-standard string functions listed in <xref
    linkend="functions-binarystring-sql"/>.
   </para>

   <table id="functions-binarystring-other">
    <title>Other Binary String Functions</title>
    <tgroup cols="1">
     <thead>
      <row>
       <entry role="func_table_entry"><para role="func_signature">
        Function
       </para>
       <para>
        Description
       </para>
       <para>
        Example(s)
       </para></entry>
      </row>
     </thead>

     <tbody>
      <row>
       <entry role="func_table_entry"><para role="func_signature">