2.2.2.6.1 Schema

   <xs:complexType name="FieldRefDefinitionGroupBy">
     <xs:attribute name="ID" type="UniqueIdentifierWithOrWithoutBraces" use="optional" />
     <xs:attribute name="Name" type="xs:string" />
     <xs:attribute name="Ascending" type="TRUE_Case_Insensitive_Else_Anything" use="optional" default="FALSE" />
   </xs:complexType>