Comment on draft-creed-ogc-urn

When I read
      OGC may permit use of experimental type values that will not be
      registered.  As a consequence, multiple users may end up using the
      same value for separate uses.  As experimental usage is only
      intended for testing purposes, this should not be a real issue.

I find the idea of URN that aren't unique sort of disturbing. We have past
experience with experiments that become widely successful and then are so
embedded in deployed code that the identifier can not be changed.