| Re: [railml3] Proposing new @epsgCode for <geometricPositioningSystem> [message #4128 is a reply to message #3970] |
Thu, 27 August 2026 13:35   |
Thomas Nygreen
Messages: 137
Registered: March 2008
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Senior Member |
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Dear Mathias,
Based on your feedback, we have decided not to go forward with the original proposal, and instead change the type of crsDefinition to xs:anyURI, as well as providing some recommendations both in the attribute documentation and in the best practice section in the wiki. The syntactic changes will appear in 3.4-beta5.
Proposed attribute documentation:
Reference to a coordinate reference system (CRS) in the form of a URI. It is strongly recommended to use the URIs maintained by Open Geospatial Consortium (OGC) under the http://www.opengis.net/def/crs/ namespace.
Proposed best practice (in the wiki):
railML.org recommends specifying the value of crsDefinition as an URL that resolves to a coordinate reference system (CRS) definition. When using a CRS listed by Open Geospatial Consortium (OGC) under the http://www.opengis.net/def/crs/ namespace, this is the preferred URI. This includes all EPGS and OGC CRS definitions. For instance, the quite common EPSG code 4326, also known as "WGS 84", has the URI https://www.opengis.net/def/crs/EPSG/0/4326. Be mindful of using a 2D CRS when you are providing 2D coordinates (geometricCoordinate with x and y) and a 3D CRS when you are providing 3D coordinates (geometricCoordinate with x, y and z). For instance, the 3D WGS 84 has the URI https://www.opengis.net/def/crs/EPSG/0/4979.
Best regards,
Thomas
(Edited 2026-09-04 to exclude sentence periods from URLs)
Thomas Nygreen – Common Schema Coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org
[Updated on: Fri, 04 September 2026 14:03] Report message to a moderator |
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