<xs:simpleType name="IfcUnitEnum">
    <xs:restriction base="xs:string">
      <xs:enumeration value="ABSORBEDDOSEUNIT"/>
      <xs:enumeration value="AMOUNTOFSUBSTANCEUNIT"/>
      <xs:enumeration value="AREAUNIT"/>
      <xs:enumeration value="DOSEEQUIVALENTUNIT"/>
      <xs:enumeration value="ELECTRICCAPACITANCEUNIT"/>
      <xs:enumeration value="ELECTRICCHARGEUNIT"/>
      <xs:enumeration value="ELECTRICCONDUCTANCEUNIT"/>
      <xs:enumeration value="ELECTRICCURRENTUNIT"/>
      <xs:enumeration value="ELECTRICRESISTANCEUNIT"/>
      <xs:enumeration value="ELECTRICVOLTAGEUNIT"/>
      <xs:enumeration value="ENERGYUNIT"/>
      <xs:enumeration value="FORCEUNIT"/>
      <xs:enumeration value="FREQUENCYUNIT"/>
      <xs:enumeration value="ILLUMINANCEUNIT"/>
      <xs:enumeration value="INDUCTANCEUNIT"/>
      <xs:enumeration value="LENGTHUNIT"/>
      <xs:enumeration value="LUMINOUSFLUXUNIT"/>
      <xs:enumeration value="LUMINOUSINTENSITYUNIT"/>
      <xs:enumeration value="MAGNETICFLUXDENSITYUNIT"/>
      <xs:enumeration value="MAGNETICFLUXUNIT"/>
      <xs:enumeration value="MASSUNIT"/>
      <xs:enumeration value="PLANEANGLEUNIT"/>
      <xs:enumeration value="POWERUNIT"/>
      <xs:enumeration value="PRESSUREUNIT"/>
      <xs:enumeration value="RADIOACTIVITYUNIT"/>
      <xs:enumeration value="SOLIDANGLEUNIT"/>
      <xs:enumeration value="THERMODYNAMICTEMPERATUREUNIT"/>
      <xs:enumeration value="TIMEUNIT"/>
      <xs:enumeration value="VOLUMEUNIT"/>
      <xs:enumeration value="USERDEFINED"/>
    </xs:restriction>
  </xs:simpleType>