<xs:simpleType name="csSourceType">
  <xs:annotation>
    <xs:documentation>The type of coordinate system source (can be predefined, external, userdefined or undefined)</xs:documentation>
  </xs:annotation>
  <xs:restriction base="xs:NMTOKEN">
    <xs:enumeration value="predefined"/>
    <xs:enumeration value="external"/>
    <xs:enumeration value="userdefined"/>
    <xs:enumeration value="undefined"/>
  </xs:restriction>
</xs:simpleType>