SSAmples

[Markus Dolensky]

Hi Jonathan,

We're already down to only 2 out of some 30 items after a single iteration:

> [...] it seems to be redundant since PARAM is allowed directly
> within a GROUP, so I've stayed with not using PARAMref.

Section 4.7 of the VOTable spec says
(http://www.ivoa.net/Documents/PR/VOTable/VOTable-20040608.html#ToC31)

"... However, in order to avoid any confusion with the previous version of 
VOTable which did not know the GROUP, all FIELDs are always defined outside any 
group, and the GROUP designates its member fields via FIELDref elements."

It seems above rule prevents FIELDs in a GROUP (and hence also PARAM which in 
the SSA context it is the special case of a constant column like an invariant 
systematic error). Otherwise, I would support your approach.


 > In the particular case of Quality, I'm not sure what you mean
 > by "combine quality flags".

The question was whether Quality is a single value/cell comprised of N integers 
that are concatenated somehow similar to a bit mask, or whether there are N 
separate boolean values/cells.

Your example shows that the latter is the case.

Clarified.

 > <GROUP utype="Quality">
 >  <PARAM name="WaveQuality" utype="Quality.1" ucd="meta.code.qual;em.wl" 
value="1">
 >   <DESCRIPTION>Quality flag for wavelength value</DESCRIPTION>
 >  <PARAM name="AstrometricQuality" utype="Quality.2" 
ucd="meta.code.qual;pos.eq" value="4">
 >   <DESCRIPTION>Quality flag for astrometric solution</DESCRIPTION>
 > </GROUP>

Markus