XML schema fails on self-referencing type.

SELECT XMLISVALID('<root><child/></root>',

  '<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

     <xs:complexType name="T">

       <xs:sequence><xs:element name="child" type="T"/></xs:sequence>

     </xs:complexType>

     <xs:element name="root" type="T"/></xs:schema>');