<xs:attribute name="Gender" use="optional"> <xs:annotation> <xs:documentation xml:lang="en">Identifies the gender.</xs:documentation> </xs:annotation> <xs:simpleType> <xs:restriction base="xs:NMTOKEN"> <xs:enumeration value="Male" /> <xs:enumeration value="Female" /> <xs:enumeration value="Unknown" /> </xs:restriction> </xs:simpleType> </xs:attribute>