<!– 3.2.3 : 3.1

One of ref or name must be present, but not both

–> <schema xmlns=“www.w3.org/2001/XMLSchema” targetNamespace=“foo” xmlns:foo=“foo”>

<element name="foo">
        <complexType>
              <attribute name="bar" ref="foo:bar" />
        </complexType>    
</element>  

<attribute name="bar" type="string" />

</schema>