STC in VOResource records

[Ray Plante]

Hi Kevin and WG,

I'll go ahead and declare a ruling on this one.  For reference, the 
problem being addressed is summarized in 
http://www.ivoa.net/forum/registry/0612/1764.htm.  If there is any 
objection, please speak up pronto!

A publishing registry shall be responsible for creating IDs within STC 
descriptions which are globally unique.  The convention for doing this 
will be to use an ID of the following form:

    <resource's authority id>/<resource's resource key>:<coordsys key>

For example, if the resource being described has an IVOA id of 
"ivo://adil.ncsa/adil", then the following can be used as an internal STC 
id refering to the UTC-FK5-TOPO standard system:

    adil.ncsa/adil:UTC-FK5-TOPO

The STC snippet, then, would look like this:

     <stc:STCResourceProfile
          xmlns="http://www.ivoa.net/xml/STC/stc-v1.30.xsd">

        <AstroCoordSystem xlink:type="simple"
                          xlink:href="ivo://STClib/CoordSys#UTC-FK5-TOPO"
                          id="adil.ncsa/adil:UTC-FK5-TOPO"/>

        <AstroCoordArea coord_system_id="adil.ncsa/adil:UTC-FK5-TOPO">
           <AllSky/>
        </AstroCoordArea>

     </stc:STCResourceProfile>

If you have objections to this, please speak up now.

I will note that I have discussed with Arnold a change to the STC schema 
which would, for practical purposes, eliminate this problem in the context 
of the registry (and other similar applications like VOEvent).  This 
alternative was suggested in part by Ed Shaya (see 
http://www.ivoa.net/forum/registry/0612/1773.htm).  It uses XLink for both 
internal and external linking.  In the rare case in which a non-standard 
coordinate system were described (rather than simply referenced) then the 
above convention would, in principle, still need to be invoked.  Arnold is 
mulling this idea over.

cheers,
Ray