[QUANTITY] moving on

[Jonathan McDowell]

> let's put Quantity on hold for the moment and start 
modelling some real things

I think those of us who think Q will be useful can still
agree on a Q model, of course all these things are subject
to revision. But given your views, I am eager to hear your
ideas on the Observation model, which may be the place to focus
since that will flow down requirements for the smaller objects.
Then we'll see if we end up using Q there or just its smaller
pieces like Frame and Accuracy.

> Agreed.  Shall we start with XML?

I think a pure XML serialization is the first thing to do.
However, I'm also working on a response to Alberto's UTYPE
message for those who like to use VOTABLE and I hope to
get that out soon.
  - Jonathan