Mention version portability of pg_dump.

doc/src/sgml/ref/pg_dump.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/pg_dump.sgml,v 1.84 2006/05/06 23:25:37 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/pg_dump.sgml,v 1.85 2006/05/13 16:19:54 momjian Exp $
 PostgreSQL documentation
 -->
 
@@ -645,6 +645,17 @@ CREATE DATABASE foo WITH TEMPLATE template0;
    ensure good performance.
   </para>
 
+  <para>
+   Because <application>pg_dump</application> is used to tranfer data
+   to newer versions of <productname>PostgreSQL</>, the output of
+   <application>pg_dump</application> can be loaded into
+   newer versions of <productname>PostgreSQL</>.  It also can read older
+   <productname>PostgreSQL</> databases.  However, it usually cannot
+   read newer <productname>PostgreSQL</> databases or produce dump output
+   that can be loaded into older database versions.  To do this, manual
+   editing of the dump file might be required.
+  </para>
+
  </refsect1>
 
  <refsect1 id="pg-dump-examples">