<xs:complexType name="IfcBuildingStoreyType">
    <xs:complexContent>
      <xs:extension base="uro:IfcSpatialStructureElementType">
        <xs:sequence>
          <xs:element name="elevation" minOccurs="0" type="gml:LengthType"/>
        </xs:sequence>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>