SSA/SDM: ucds and namespaces

[Ulrike Stampa]

Hi Doug,

trying to implement an SSA service I still have some questions
concerning the contents of the votable which my service is supposed to
return:
In the SSA Data Model Summary in appendix D of SSAP V 1.02 I feel some
ucds are missing:  e.g. Dataset.DataModel (might be "meta.version"?),
Dataset.SpectralSI ("meta.unit;em.wl"?), Dataset.FluxSI"
("meta.unit;phot.flux"?). Any special reason for that?

In the section "Protocol" of the summary table (on first page) there are
two namespaces defined for SSA and spectrum data model. Does this mean
the  utypes in the queryResponse and metadataResponse must have exactly
these prefixes? Or can I use any prefix, just make sure it defines the
SSAP namespace rsp. the Spectrum Data Model namespace?

Where do I need the Spectrum Data Model namespace? Up to now I only used
SSA - utypes. I still do not see the difference. To me it looks like the
SSAP  subsumes the  spectrum data model. (I admit, I haven't studied it
thouroughly.)

Thanks!
Best regards
Ulrike Stampa, GAVO