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Ethan: The structure of a URN is so that you can create one - NOT so that they are parsed for content. I think the fuzziness at the OGC in this regard is simple mistaken. GML is used now in the http://www.epsg-registry.org. This registry and the assignment of EPSG codes is controlled by the registration authority, in this case the OGP. Another such registry could easily be deployed assuming that someone is willing to be the registration authority and this could have perhaps a difference governance model than used by the OGP. The 19111 new parts will make their way into GML of course. Ron
-----Original Message----- From: Ethan Davis [mailto:edavis@xxxxxxxxxxxxxxxx] Sent: October 9, 2008 12:15 PM To: Ron Lake Cc: Unidata GALEON Subject: Re: [galeon] How to map a parameterized projection to an EPSG code Hi Ron, I agree that a URN should only be an identifier. And one could argue that since they are URNs that all OGC URNs really are only identifiers. However, since the OGC CRS URN "naming" scheme is so detailed, parameterizable, and even compoundable, I think that if one cared (dared?) to parse the URNs one could figure out the definition of the CRS. So, I think for OGC CRS URNs, the line between identify and define is pretty fuzzy. I also agree that it would be good to have a way to easily register commonly used, parameterized CRS. And a grammar in which the CRS can be defined. (Is GML up to this task? Or will it be once ISO 19111-1 and -2 are folded in?) On the other hand, for less commonly used or somewhat unique CRS, making the definition available at some URL and using that URL to reference the CRS may be enough. Ethan
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