
   <schema targetNamespace="http://www.xqsharp.com/test"
           xmlns:t="http://www.xqsharp.com/test"
           xmlns="http://www.w3.org/2001/XMLSchema">

     <!--* test schema document from bug 6625,
         * courtesy of Oliver Hallam. *-->

     <element name="head" type="string" />

     <element name="sub" substitutionGroup="t:head" nillable="true" />

     <element name="root">
       <complexType>
         <sequence>
           <element ref="t:head" />
         </sequence>
       </complexType>
     </element>

   </schema>

