SCS2: POS plus RA/DEC/SR

[Markus Demleitner]

Dear DAL folks,

On Mon, Sep 14, 2026 at 04:09:37PM -0700, Patrick Dowler via dal wrote:
> A circle parameter would have a defined (DALI) xtype and value
> serialisation and be required for SCSv2; other such params (POLYGON,
> MOC, etc) could be defined now or later and be optional. Then it comes
> down to declaring which parameter names are supported (capabilities or
> service descriptors) rather than which variants of POS are supported.

Ok, so we'll replace POS with CIRCLE... and keep RA/DEC/SR as some
sort of legacy wrapper?  And require CIRCLE, including its repeated
use?

I think I'll put that into the spec unless there's loud protest just
about now.

As to Gilles' question:

> multi-cone : why not ? But what does it means ? Do we expect a
> « union «  Or a « union ALL » (so accept repetition or not).

I'm pretty sure the rules should remain as they are for the current
UPLOAD: It's a normal UNION.

To me, that's obvious because of the benefits a proper primary key
(meta.id;meta.main) gives to any sort of data; but the alternative
"multiple, possibly overlapping cones" would also only work properly
if each row said which cone matched it, and we don't have a mechanism
that does that either.

I give you at on the implementation side, the non-dupe requirement
was a bit tedious with the join-based strategy I had with UPLOAD.
Multi-CICLE I'll probably do by OR-ing together the individual
constraints, and then plain UNION is even more natural.

Thanks,

        Markus