<xs:complexType name="Source"> <xs:choice> <xs:element name="AutomatedSystem" type="ref:AutomatedSystem" /> <xs:element name="Member" type="members:MemberType" /> <xs:element name="OtherReferral" type="commons:ContactablePerson" /> </xs:choice> <xs:attribute ref="ref:description" use="optional" /> <xs:attribute ref="ref:sourceType" use="required" /> <xs:attribute name="sourceTypeOtherDescription" /> </xs:complexType>