gml:verticalDatum is an association role to the vertical datum used by this CRS.
<gml:verticalDatum xlink:actuate="" xlink:arcrole="" xlink:href="" nilReason="" gml:remoteSchema="" xlink:role="" xlink:show="" xlink:title="" xlink:type="simple"> <gml:VerticalDatum gml:id="">{1,1}</gml:VerticalDatum> </gml:verticalDatum>
<element name="verticalDatum" type="gml:VerticalDatumPropertyType"> <annotation> <documentation>gml:verticalDatum is an association role to the vertical datum used by this CRS.</documentation> </annotation> </element>