| Re: Proposal for semantic constraints for usage of GML elements [message #3814 is a reply to message #3812] |
Fri, 05 December 2025 15:20   |
Thomas Nygreen
Messages: 110
Registered: March 2008
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Senior Member |
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Dear Margo,
I agree with Mathias that GML locations are not connected to the topology or to the other *Locations provided.
If we need such a semantic constraint, we would also need it for the other *Locations. It is also currently valid to provide multiple *Locations with different geometric coordinates in the same CRS.
Another detail is that the srsName is not necessarily an EPSG code, although EPSG is the most commonly used database of CRSs, so unless we also introduce a requirement that the srsName must provide an EPSG code, we should use srsName in the wording of any constraint.
I am sceptical towards moving GML locations as they are into the other *Locations, because the other *Locations already provide geometric coordinates. The GML location currently offer two things that the other *Locations do not: (1) a geometric coordinate independent of the topology and (2) the lineString. If we decide that we do not want (1), we can maybe remove GML locations and offer a lineString as an alternative to geometricCoordinateBegin/geometricCoordinateEnd.
Best regards,
Thomas
Thomas Nygreen – Common Schema Coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org
[Updated on: Tue, 09 December 2025 14:12] Report message to a moderator |
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