calendar

<xs:simpleType name="calendar">
  <xs:restriction base="xs:string">
    <xs:enumeration value="Chinese"/>
    <xs:enumeration value="Gregorian"/>
    <xs:enumeration value="Islamic"/>
    <xs:enumeration value="ISO"/>
    <xs:enumeration value="Jewish"/>
    <xs:enumeration value="Julian"/>
  </xs:restriction>
</xs:simpleType>