VO and ADEC identifiers

[Tony Linde]

> will have those get?() methods anyway. It doesn't really effect service 
> design to say what the registry does or doesn't do since the service is 
> usable without the registry. The registry is just the way to find the 
> service(s).

I'm confused about the idea of datasets (remember that I'm not an astronomer
so please have patience). 

If there is a single service which sits in front of a collection of
datasets, each of which is a table within a database, how does a query sent
to the service work? Does it query every dataset with the same criteria? 

Are all the datasets just blocks within a single table so that a query is
effectively on the colleciton as a whole and the data returned can be from
many datasets? 

If a user queries the registry looking for a service which can provide data
of some description, how is the collection of datasets described under a
single service? - ie does the metadata (coverage, content etc) embrace all
the datasets as if they all existed in a single table?

Sorry if this is AstroInformatics 101 :)

Cheers,
Tony.