CRS Resolver Discussion

Overview

Issues Open

Issues Resolved

Abbreviation Changes in EPSG Database

• Axis abbreviation "long" has been changed to "lon" in EPSG geodetic dataset after 8.5. This is not an incompatible change since axis abbreviations are not identifiers and do not affect numerical computation; they are more like metadata. But some software are nevertheless affected by this change. For this reason, upgrading the EPSG geodetic dataset version referenced by /0/ has been temporarily delayed. Of course this entails that other EPSG changes, like new CRSs introduced, are not available this way either.
• *Preliminary resolution*:
  • the EPSG database continues to get updated in OGC; updated versions available by indicating the particular version, such as http://www.opengis.net/def/crs/EPSG/8.9.2/4326
  • version indicator "0" (earlier indicating "latest version" as an informal, non-normative convention) is temporarily fixed to version 8.5.2
• final solution, as per OGC-NA decision in March 2019:
  • version "0" shall always point to the latest version of the corresponding EPSG definition. (Caveat: this may imply unnoticed changes by EPSG)

Case Sensitivity

• Request: (Simon Cox) I just discovered that the URI redirects associated with EPSG CRS parameters are case-sensitive, so http://www.opengis.net/def/crs/EPSG/0/5711 and http://www.opengis.net/def/crs/epsg/0/5711generatedifferent responses: the former goes to SECORE, and the latter to the EPSG Indicio registry. This clearly is undesirable. They should go to the same place, and that place should be SECORE.
• Resolution: There has been discussion with OGC since April 2016, but no authoritative decision has been made. Therefore, we continue using IETF 2141 (referenced by IETF 5165), sections 5 and 6: https://tools.ietf.org/html/rfc2141 implying that SECORE should be case sensitive, as would be anything after the “ogc” namespace identifier. -- PeterBaumann - 19 Sep 2016

Redirection to the Resolver

• Request: The redirection mechanism is currently not working as expected and it seems that only EPSG related definitions actually redirected to SECORE:

1. http://www.opengis.net/def/axis/OGC/1.0/East
2. http://www.opengis.net/def/crs/
3. http://www.opengis.net/def/crs/OGC/
4. http://www.opengis.net/def/crs/ -- PieroCampalani - 25 Nov 2013

• Resolution:OGC has corrected URL redirection In October 2016.

Schema

• Request: I notice that the SECORE definitions are schema invalid (EPSG.xsd). Checking against both http://www.opengis.net/def/crs/EPSG/0/5711 and http://kahlua.eecs.jacobs-university.de:8080/def/crs/EPSG/0/5711 and reported http://rasdaman.org/ticket/732. As well as fixing this GML output, would it not be a good idea to add the EPSG.xsd file to the schemas at http://schemas.opengis.net/and use this as a schemaLocation in the XML instances? -- JamesPassmore - 31 Mar 2014
• Resolution: SECORE, in the first place, maintains URLs only. Location of such a file and its reference in the EPSG definitions needs to be clarified. Problematic is that EPSG definitions are taken "as is" and not modified in any way. Therefore, such a request best should be made to OGP. -- PeterBaumann - 21 Oct 2016

CRSdefinitionResolver Web Utilities

• WebTopicList - all topics in alphabetical order
• WebChanges - recent topic changes in this web
• WebNotify - subscribe to an e-mail alert sent when topics change
• WebRss, WebAtom - RSS and ATOM news feeds of topic changes
• WebStatistics - listing popular topics and top contributors
• WebPreferences - preferences of this web