test/schemas/src-element2-1_0.xsd

<?xml version="1.0" encoding="ISO-8859-1" ?>
<!-- 3.2.3 : 2.1 
    One of ref or name must be present, but not both.
-->
<schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://foo" xmlns:foo="http://foo">
	
  <element name="bar" type="string"/>	
	
  <element name="foo">
  	  <complexType>
  	  	<sequence>
  	  		<element name="bar" ref="foo:bar"/>	   
  	  	</sequence>
  	  </complexType>    
  </element>  

</schema>