<xs:simpleType name="ST_Guid" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:restriction base="ST_String"> <xs:pattern value="[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}" /> </xs:restriction> </xs:simpleType>