SODA, half-client and remaining gripe collection

[Mark Taylor]

On Tue, 29 Mar 2016, Markus Demleitner wrote:

> (6) @value="" universally valid
> 
> VOTable 1.3 says "If the TD element is empty (<TD/> or <TD></TD>) the
> cell is considered to contain no data, i.e. to be null."  Since we're
> saying "parse PARAM/@value like you parse TABLEDATA cells" (I really
> think VOTable itself should say this in sect. 4.1, last bullet point), I
> *think* we're fine saying "Generate your UI from all the PARAMs that
> have value="" (which, in effect, we're doing right now and we'd
> certainly be doing if we adopt (5).  I'd much prefer if that were made
> explicit somewhere.  Bug me for a doc patch if everyone interested agrees.

It is probably true that VOTable ought to specify this.
However, it's not too surprising that it doesn't.
This use of PARAM to document service parameters comes pretty close
to abuse of the PARAM element; the fact that 'PARAM' sounds a bit like
'service-parameter' is entirely coincidental, a PARAM element is
intended to contain some per-table metadata, which historically
has been known as a "table parameter".  So specifying a PARAM
with a null value looked like a pretty strange thing to do in
the context of the original VOTable specification.
That's also the reason that the @value attribute is mandatory.

--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/