Relationship with ISO 19107 General concepts

56 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. gml:name and a description elements gml:description and gml:descriptionReference 2 . It may be associated with a spatial reference system attribute group gml:SRSReferenceGroup. The following rules shall be adhered to:  Every geometry type shall derive from this abstract type.  Every geometry element i.e. an element of a geometry type shall be directly or indirectly in the substitution group of AbstractGeometry.

10.1.3.2 SRSReferenceGroup

attributeGroup name=SRSReferenceGroup attribute name=srsName type=anyURI attribute name=srsDimension type=positiveInteger attributeGroup ref=gml:SRSInformationGroup attributeGroup The attribute group gml:SRSReferenceGroup is an optional reference to the CRS used by this geometry, with optional additional information to simplify the processing of the coordinates when a more complete definition of the CRS is not needed. In general the attribute srsName points to a CRS instance of gml:AbstractCoordinateReferenceSystem see 12.2.3. For well-known references it is not required that the CRS description exists at the location the URI points to. If no srsName attribute is given, the CRS shall be specified as part of the larger context this geometry element is part of. EXAMPLE A geometric aggregate or a feature collection are typical ―larger contexts‖. NOTE The name ―srsName‖ has been chosen deliberately. In the current version of GML ―crsName‖ would be more appropriate, however, in future versions other types of spatial reference system, i.e. those using geographic identifiers, may be supported by GML, too. The optional attribute srsDimension is the number of coordinate values in a position. This dimension is derived from the coordinate reference system. When the srsName attribute is omitted, this attribute shall be omitted.

10.1.3.3 SRSInformationGroup

attributeGroup name=SRSInformationGroup attribute name=axisLabels type=gml:NCNameList attribute name=uomLabels type=gml:NCNameList attributeGroup The attributes uomLabels and axisLabels, defined in the gml:SRSInformationGroup attribute group, are optional additional and redundant information for a CRS to simplify the processing of the coordinate values when a more complete definition of the CRS is not needed. This information shall be the same as included in the complete definition of the CRS, referenced by the srsName attribute. When the srsName attribute is included, either both or neither of the axisLabels and uomLabels attributes shall be included. When the srsName attribute is omitted, both of these attributes shall be omitted. 2 Deprecated properties have been omitted from this list. Nevertheless, they are still valid content.