doc: document "IS NOT DOCUMENT"

Reported-by: [email protected]
Discussion: https://postgr.es/m/152056505045.4963.16783351661813640274@wrigleys.postgresql.org

Author: Euler Taveira

Backpatch-through: 9.3

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index e54428d58d78b97c8506557c1fb1a704e40b12c5..1a5429a6ea34fee39cab0e5ce2ffcc134636ac29 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -9499,6 +9499,24 @@ SELECT xmlagg(x) FROM (SELECT * FROM test ORDER BY y DESC) AS tab;
     </para>
    </sect3>
 
+   <sect3>
+    <title><literal>IS NOT DOCUMENT</literal></title>
+
+    <indexterm>
+     <primary>IS NOT DOCUMENT</primary>
+    </indexterm>
+
+<synopsis>
+<replaceable>xml</replaceable> IS NOT DOCUMENT
+</synopsis>
+
+    <para>
+     The expression <literal>IS NOT DOCUMENT</literal> returns false if the
+     argument XML value is a proper XML document, true if it is not (that is,
+     it is a content fragment), or null if the argument is null.
+    </para>
+   </sect3>
+
    <sect3 id="xml-exists">
     <title><literal>XMLEXISTS</literal></title>