ifc:IfcSequenceEnum

<xs:simpleType name="IfcSequenceEnum">
  <xs:restriction base="xs:string">
    <xs:enumeration value="start_start"/>
    <xs:enumeration value="start_finish"/>
    <xs:enumeration value="finish_start"/>
    <xs:enumeration value="finish_finish"/>
    <xs:enumeration value="userdefined"/>
    <xs:enumeration value="notdefined"/>
  </xs:restriction>
</xs:simpleType>