It is not possible to query SIA services by MOC

[Bonnarel]

MOC (as well as STMOC, and maybe STEMOC) has proven to be a very efficient way to describe coverage of data and is used for discovery of data. It has been often discussed and also during last interop that it should be useful to query SIA services by MOC ? It should probably be with a new parameter and not via POS considering that it is probably more useful to have STMOC or STEMOC, than spatial MOC alone. This is also valid for SODA of course (ivoa-std/SODA#5). I wonder if this new parameter should not be standardized by DALI

[pdowler]

Since WD-DALI-1.2 defines a "moc" xtype, I support adding a MOC param to go along with the other axis query params. It is true that the "overlap" of a MOC param and POS, BAND, TIME is non-trivial.

Also, WD-DALI-1.2 refers to MOC-1.x (spatial moc) so we'll need to revisit that and decide if we need 1 or more moc xtype(s).

I also agree we should consider this together with SODA axis params and figure out if it's worth defining them in a single common place (DALI). My gut feeling is thatb we can keep SIA (SDA) and SODA consistent without that, but if there is a 3rd use of these params then maybe refactoring to DALI is a good idea.