By following the links on http://www.opengis.net/def/crs/ one can download identifiers/IRIs for various CRSes minted by the OGC. For many CRSes, there seem to be multiple identifiers, differing in what looks like a version number. E.g., for
http://www.opengis.net/def/crs/EPSG/0/2000 http://www.opengis.net/def/crs/EPSG/8.5/2000 http://www.opengis.net/def/crs/EPSG/8.9.2/2000 http://www.opengis.net/def/crs/EPSG/9.4.2/2000 http://www.opengis.net/def/crs/EPSG/9.5/2000 http://www.opengis.net/def/crs/EPSG/9.5.3/2000
Does anybody know what these version-like numbers refer to? The OGC GeoSPARQL standard uses IRIs with
0 (i.e., the first IRI in the above list), but does not explain what the
0 stands for.