The gml:axis property is an association role (ordered sequence) to the coordinate system axes included in this coordinate system. The coordinate values in a coordinate tuple shall be recorded in the order in which the coordinate system axes associations are recorded, whenever those coordinates use a coordinate reference system that uses this coordinate system. The gml:AggregationAttributeGroup should be used to specify that the axis objects are ordered.
<element name="axis" type="gml:CoordinateSystemAxisPropertyType"><annotation><documentation>The gml:axis property is an association role (ordered sequence) to the coordinate system axes included in this coordinate system. The coordinate values in a coordinate tuple shall be recorded in the order in which the coordinate system axes associations are recorded, whenever those coordinates use a coordinate reference system that uses this coordinate system. The gml:AggregationAttributeGroup should be used to specify that the axis objects are ordered.</documentation></annotation></element>