 <p>You may want to look at example 17-2 on the following site since it looks to cover what you are trying to do <a href="http://www.datypic.com/books/defxmlschema/chapter17.html" rel="nofollow">http://www.datypic.com/books/defxmlschema/chapter17.html</a>.</p> <p>EDIT: The feedback is that the key does need to be unique, so I'm removing that part of my response to avoid confusion.</p>