SSA UTYPES

[Alberto Micol]

Dear Doug and Jonathan,

The paragraph 3.3.6 Query Response Metadata of the SSA0.97 document  
states
that the leading "spectrum." in the UTYPE for a Spectrum data model  
attribute
should be omitted, the reason being that SSA metadata do not need to  
be specific
to spectra.

In such case, shouldn't SSA have its own model/name space?
I do not think we want to have UTPYEs not associated to a model, do we?


Then in the Appendices (both A and B) one reads:

<VOTABLE ... xmlns:sdm="http://www.ivoa.net/xml/SpectralDataModel/ 
v1.0"...>

[...]

<FIELD name="upper/lower bounds of spectral bandwidth"
         datatype="float" arraysize="2" ID="boundsSpectral"
====>   utype="sdm:SSA.Coverage.Bounds.Spectral"
         ucd="instr.bandwidth" unit="Angstrom"/>
[...]

(well, the correct utype should be  
sdm:SSA.Char.SpectralAxis.Coverage.Bounds.Extent
instead, but that is not the point...)
The point is that the votable declares the SDM name space, but then  
the utype used
is not SDM nor SSA compliant, because SDM does not know the "SSA."  
prefix,
and because SSA dictates that the word "Spectrum." should be dropped.

To recap, depending on whether if I follow :

1. the statement in SSA 3.3.6,
2. the SSA Appendix,
3. the SDM v1 rel cand 1 rev 2

I can come up with three (or maybe four) different utypes for
the same field:

1.  sdm:SSA.Char.SpectralAxis.Coverage.Bounds.Extent

        which is wrong because sdm wants "Spectrum." and not "SSA."
        What is probably meant here is instead:

1'. ssa:Char.SpectralAxis.Coverage.Bounds.Extent

        which means that an SSA name space is to be introduced

2.  sdm:Char.SpectralAxis.Coverage.Bounds.Extent

        but this we know to be wrong: sdm requires "Spectrum."

3.  sdm:Spectrum.Char.SpectralAxis.Coverage.Bounds.Extent

        at this point in time this one seems to me the only  
reasonable one,
        until of course we get the characterisation data model approved.
        But in the mean time we have to get the ball rolling...

Could you please clarify?

Thanks,

Alberto
PS: BTW, I support Randy's comments that the examples given in the  
Appendixes
are really important to the developers. It would be so nice to have them
fully thought through, so to act as approved references that one  
could use
and adapt to his/her case... It would speed up development!