instr.fov in SSAP

[Markus Demleitner]

Dear Colleagues,

SSAP 1.1 requires the UCD instr.fov on a few columns (cf. p.66 of
https://ivoa.net/documents/SSA/20120210/REC-SSA-1.1-20120210.pdf).

Trouble is: By UCDList 1.4, instr.fov is a secondary UCD, so the
UCD required by SSA is illegal by UCD.

How do we fix this?  I see two ways forward: Either we lift the S
restriction on instr.fov. This would sound reasonable to me and
obviously many others; here's a few counts from today's
rr.table_columns:

 instr.fov                                 |  198
 instr.fov;instr.pixel                     | 2475
 phys.angsize;instr.fov                    |  167
 pos.angdistance;instr.fov                 |   16
 pos.posang;instr.fov                      |   12

(these are the most popular ones).

Or we write an erratum to SSAP changing the required UCD to, I think,
phys.angsize;instr.fov .

Me, I don't have much of an opinion, though I have to admit I can't
really say why there's the S on instr.fov.


There is a similar problem in SLAP, where a UCD em.line is required,
which also is S in the UCD list.  I'd be a lot more relaxed about
that since I believe SLAP as a whole ought to make room for something
closer to VAMDC.


Thanks,

          Markus