diff -cprN head/doc/src/sgml/ddl.sgml work/doc/src/sgml/ddl.sgml
*** head/doc/src/sgml/ddl.sgml	2010-02-25 09:58:18.518068000 +0900
--- work/doc/src/sgml/ddl.sgml	2010-03-31 15:46:11.748532000 +0900
*************** CREATE TABLE order_items (
*** 845,850 ****
--- 845,880 ----
      <xref linkend="sql-createtable" endterm="sql-createtable-title">.
     </para>
    </sect2>
+ 
+   <sect2>
+    <title>Exclusion constraints</title>
+ 
+    <indexterm>
+     <primary>exclusion constraint</primary>
+    </indexterm>
+ 
+    <indexterm>
+     <primary>constraint</primary>
+     <secondary>exclusion</secondary>
+    </indexterm>
+ 
+    <para>
+     Exclusion constraints ensure that if any two rows are compared on
+     the specified columns or expressions using the specified operators,
+     at least one of these operator comparisons will be false. The syntax is:
+ <programlisting>
+ CREATE TABLE circles (
+     c circle,
+     EXCLUDE USING gist (c WITH &amp;&amp;)
+ );
+ </programlisting>
+    </para>
+ 
+    <para>
+     See also <link linkend="SQL-CREATETABLE-EXCLUDE"><command>CREATE
+     TABLE ... CONSTRAINT ... EXCLUDE</></link> for details.
+    </para>
+   </sect2>
   </sect1>
  
   <sect1 id="ddl-system-columns">