From: <glassfish_at_javadesktop.org>
Date: Mon, 09 Mar 2009 06:29:12 PDT

A simple google shows that the default value for minOccurs and maxOccurs is 1 for elements, giving you exactly what you need.
[Message sent by forum member 'matterbury' (matterbury)]

http://forums.java.net/jive/thread.jspa?messageID=335843