SimpleDALRegExt 1.2 WD

[Markus Demleitner]

Dear Registry Community,

With quite a bit of delay I've now uploaded to the document
repository the new version of SimpleDALRegExt promised in Groningen,
and I'd be grateful for any feedback --

http://ivoa.net/documents/SimpleDALRegExt/20200212/

The reason for this update, really, is that the TCG wanted the #aux
standard identifiers for the S*APs that are mentioned in the endorsed
note on discovering data collections where implementors would
actually notice them.  They are now in section 4.

While I was touching the document, I found two other spots of
trouble:

* there was a SpaceFrame type used for the definition of SSAP
  services.  Since that listed a load of frames that we will
  (probably) no longer have in STC2, and we want to migrate the list
  of frames to a vocabulary anyway, I've removed the type and
  replaced it with a pointer to the vocabulary
  http://ivoa.net/rdf/refframe/ instead.  Nothing will become
  schema-broken by this move, but if validators start validating
  against the vocabulary, legacy records might become invalid.  In
  reality, that won't happen because no registred services use any of
  the dropped frames, so I'd plead we're on the good side of standard
  evolution with this move.

* SimpleDALRegExt 1.0, of 10 years ago, had a ProtoSpectralAccess
  type that was deprecated immediately in the REC.  Back in last
  autumn, the last publishers still publishing records that used the
  time pulled them from the Registry, and so, again, I'd say we're
  fine to just drop this type, even though it would invalidate
  records -- it's just that such records don't exist any more.

So... Opinions?  Ideas for other cleanup we should be doing while
we're at it?

Unless there's discussion, I'd ask the chairs to push this to PR rather
soon (as in mid-March), as the changes, really, are trivial in
practice.  The core is a consequence of things the TCG has already
endorsed (DDC), and the rest is pure cleanup and simplification.

         -- Markus