MCT - model document delivery.

[Markus Demleitner]

Dear DM,

I've saved this reply until other subthreads had died down; let me
just quickly round this off for the archive after
http://mail.ivoa.net/pipermail/dm/2020-September/006127.html

On Tue, Sep 22, 2020 at 10:22:49AM -0400, CresitelloDittmar, Mark wrote:
> On Mon, Sep 21, 2020 at 4:51 AM Markus Demleitner <
> msdemlei at ari.uni-heidelberg.de> wrote:
> > On Fri, Sep 18, 2020 at 11:00:03AM -0400, CresitelloDittmar, Mark wrote:
> > [the following refers to this:]
> > > >    <INSTANCE type="ds:Target">
> > > >      <COLLECTION role="targetPosDef">
> > > >       <INSTANCE ref="RA"/>
> > > >       <INSTANCE ref="DEC"/>
> > > >      </COLLECTION>
> > > >      <ATTRIBUTE role="objectClass" value="Star"/>
> > > >    </INSTANCE>
> >
> >  <snip>
> 
> > >           * which is the latitude? the longitude? the frame?
> >
> > Target does not know about them, nor should it.  A target is a
> > target, whether it is identified by a coords spherical position or
> > some other way to denote a location in.  The good thing about keeping
> > such details out of ds:Target is that it will just continue to work
> > when we're moving into the solar system (where lat and long just
> > isn't enough).  Just say which fields and params belong to the target
> > designation and leave their annotation to a specialised class.
> >
> 
> In your vision then, what does the model element ds:Target contain?
> I don't mean the annotation, the model.  The current model has
>  ds:Target
>     + name: ivoa:string
>     + description: ivoa:string
>     + position: meas:Position[0..1]
>     + objectClass: ivoa:string

It's been a while since I've thought about VO-DML in any depth, but
if it doesn't have something equivalent to "FIELD or PARAM in VOTable
(or equivalent in other containers)", it would be easy to add a
ivoa:any type:

  position_components: ivoa:any[0..n]

       -- Markus