test/schemas/ns2_0.xsd

<schema xmlns:my='http://my.ns/'
        xmlns='http://www.w3.org/2001/XMLSchema'
	targetNamespace='http://my.ns/'
	>
 <attribute name='other' type='string'/>
 <element name='my'>
   <complexType>
     <simpleContent>
       <extension base='string'>
         <attribute ref='my:other'/>
       </extension>
     </simpleContent>
   </complexType>
 </element>
</schema>