TAP 1.0: sync vs async

[Gerard]

Hi Paul
> I also support this idea - in fact I would go further (as 
> also recently suggested by Tom) and say that the sync and 
> async should also be registered as separate Capabilities, and 
> thus potentially on totally separate machines, rather than 
> being forced into the single URL tree.
> 
I agree, this was missing in the proposal. 
It would be good to be able to find out explicitly from service metadata
whether one can send sync and/or async queries.

Gerard