Spectral DM 2.0: TCG review feedback

[Markus Demleitner]

Dear DM,

On Mon, Dec 01, 2014 at 04:37:53PM -0500, CresitelloDittmar, Mark wrote:
> I think it's OK if any discussion happens on the DM list.
> I wanted the announcement to be more broad so all concerned were aware of
> the update.
> 
> I have, to date, kept the multiplicity out of the heading lines, as they
> are already in the diagrams and descriptions.
> If it is to be added, I like how you placed the multiplicity on the
> attribute "Curation.reference[0..*] : String" rather than on the type
> "Curation.reference : String [0..*]"

Well, I'm not really concerned with putting this more prominently in
the headlines, and I believe it'd be typographically, erm,
unfavourable.  What I'm concerned with is that from the document,
it's not very clear how to actually write items of multiplicity >1,
either generically or separately for each format.

One possibility would be to say in the appendix on FITS:

  If multiple values for an attribute need to be represented, append
  number so each keyword; for instance 
  REFERENCE1 foo
  REFERENCE2 bar

  Use HIERARCH if the keywords become too long in this way

In VOTable, you might get away with just repeating the params.

Note that I'm not actually proposing this; all effort spent here
would be better spent ironing out the wrinkles in the general DM
serialisation within the VO-DML effort, not the least because all
this totally explodes anyway when there are non-atomic attributes of
multiplicity >1 (are there in SDM2?).

> Another option, which would be a larger change, could be to reformat the
> entries to isolate the items.. more in the direction of what VODML

Again, I don't think this is a formatting issue.  As far as I am
concerned, this is a very fundamental issue in the proposed
serialisations, and it is a major part of why I'd like to see at
least examples exercising all the features that are in Spectrum
DM; writing these up is the only way to figure out spots of
trouble like the 0..* attribute case.

Cheers,

         Markus