diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
new file mode 100644
index 53021c2..e79c479
*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
*************** SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1
*** 6570,6575 ****
--- 6570,6589 ----
         <row>
          <entry>
           <indexterm>
+           <primary>date_trunc</primary>
+          </indexterm>
+          <literal><function>date_trunc(<type>text</type>, <type>interval</type>)</function></literal>
+         </entry>
+         <entry><type>interval</type></entry>
+         <entry>Truncate to specified precision; see also <xref linkend="functions-datetime-trunc">
+         </entry>
+         <entry><literal>date_trunc('hour', interval '2 days 3 hours 40 minutes')</literal></entry>
+         <entry><literal>2 days 03:00:00</literal></entry>
+        </row>
+ 
+        <row>
+         <entry>
+          <indexterm>
            <primary>extract</primary>
           </indexterm>
           <literal><function>extract</function>(<parameter>field</parameter> from