flag letters defined by XQuery are
        related to but not the same as the option letters for POSIX
        (<xref linkend="posix-embedded-options-table"/>).  While the
        <literal>i</literal> and <literal>q</literal> options behave the
        same, others do not:
        <itemizedlist>
         <listitem>
          <para>
           XQuery's <literal>s</literal> (allow dot to match newline)
           and <literal>m</literal> (allow <literal>^</literal>
           and <literal>$</literal> to match at newlines) flags provide
           access to the same behaviors as
           POSIX's <literal>n</literal>, <literal>p</literal>
           and <literal>w</literal> flags, but they
           do <emphasis>not</emphasis> match the behavior of
           POSIX's <literal>s</literal> and <literal>m</literal> flags.
           Note in particular that dot-matches-newline is the default
           behavior in POSIX but not XQuery.
          </para>
         </listitem>
         <listitem>
          <para>
           XQuery's <literal>x</literal> (ignore whitespace in pattern) flag
           is noticeably different from POSIX's expanded-mode flag.
           POSIX's <literal>x</literal> flag also
           allows <literal>#</literal> to begin a comment in the pattern,
           and POSIX will not ignore a whitespace character after a
           backslash.
          </para>
         </listitem>
        </itemizedlist>
       </para>
      </listitem>
     </itemizedlist>
    </para>

   </sect3>
  </sect2>
 </sect1>


  <sect1 id="functions-formatting">
   <title>Data Type Formatting Functions</title>

   <indexterm>
    <primary>formatting</primary>
   </indexterm>

   <para>
    The <productname>PostgreSQL</productname> formatting functions
    provide a powerful set of tools for converting various data types
    (date/time, integer, floating point, numeric) to formatted strings
    and for converting from formatted strings to specific data types.
    <xref linkend="functions-formatting-table"/> lists them.
    These functions all follow a common calling convention: the first
    argument is the value to be formatted and the second argument is a
    template that defines the output or input format.
   </para>

   <table id="functions-formatting-table">
    <title>Formatting 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">
        <indexterm>
         <primary>to_char</primary>
        </indexterm>
        <function>to_char</function> ( <type>timestamp</type>, <type>text</type> )
        <returnvalue>text</returnvalue>
       </para>
       <para role="func_signature">
        <function>to_char</function> ( <type>timestamp with time zone</type>, <type>text</type> )
        <returnvalue>text</returnvalue>
       </para>
       <para>
        Converts time stamp to string according to the given format.
       </para>
       <para>
        <literal>to_char(timestamp '2002-04-20 17:31:12.66', 'HH12:MI:SS')</literal>
        <returnvalue>05:31:12</returnvalue>
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <function>to_char</function> ( <type>interval</type>, <type>text</type> )
        <returnvalue>text</returnvalue>
       </para>
       <para>
        Converts interval to string according to the given format.
       </para>
       <para>
       <literal>to_char(interval '15h 2m 12s', 'HH24:MI:SS')</literal>
       <returnvalue>15:02:12</returnvalue>
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <function>to_char</function> ( <replaceable>numeric_type</replaceable>,