ifc:IfcFlowDirectionEnum

<xs:simpleType name="IfcFlowDirectionEnum">
  <xs:restriction base="xs:string">
    <xs:enumeration value="source"/>
    <xs:enumeration value="sink"/>
    <xs:enumeration value="sourceandsink"/>
    <xs:enumeration value="notdefined"/>
  </xs:restriction>
</xs:simpleType>