ifc:IfcConstraintEnum

<xs:simpleType name="IfcConstraintEnum">
  <xs:restriction base="xs:string">
    <xs:enumeration value="hard"/>
    <xs:enumeration value="soft"/>
    <xs:enumeration value="advisory"/>
    <xs:enumeration value="userdefined"/>
    <xs:enumeration value="notdefined"/>
  </xs:restriction>
</xs:simpleType>