Official GML profiles are now being widely discussed and it is more or less a certainty that some of these will be official OGC specifications in the coming months. Remember that GML was intended to be profiled and that a subset tool has been included in the specification since GML v3.0. This tool enables one to readily create profiles on which particular types of application schemas can be built. Use of profiles enables particular application domains and types of applications to only use the GML components that they need and disregard the rest. Don't need CRS schemas – well then don't use them. Don't need topology? Don't need coverages? Then profiles can be quickly tailored for these requirements. The point of profiles from a specification viewpoint is simply to provide a named reference to the profle and some simple documentation that appeals to a particular group of users. I can say then "we support the Point profile" or we support the "GMLJP2 profile" or we support the "simple geometry profile" and so on. To make this discussion more concrete I will describe a few simpe profiles including:
- Point only
- Simple geometry
- Web publishing
These profiles have no OGC status and are NOT OGC specifications. They are, however, perfectly valid profiles of GML and any general GML software (e.g. Galdos GML SDK) will be able to process them or data instances that conform to application schemas constructed on any of these profiles.
Just to give you a heads up, these profiles will contain the following elements:
This will contain ONLY gml:Point
This will contain only gml:Point, gml:LineString, gml:LinearRing, gml:Point.
This will contain the Simple Geometry as above, some time elements  (see this blog), and gml:Observation . This allows to record things like "I took this picture here" or "I recorded this sound here and at this time".