[QUANTITY] Quantity "arguments"

[amicol at eso.org]

Quoting David Berry <dsb at ast.man.ac.uk>:

 
> By the way - you, Brian and I seem to have talked everyone else out of
> this discussion! Is anyone else still following these threads?
> 
> David
>

I'm trying to follow, but sometimes I got confused. 
If we are speaking of what a WCS is, then I'm with you David: 

> I would prefer to see WCS modelled as "a set of algorithms [which may need
> to refer to numerical values]" (i.e. a FrameSet) rather than as "a set of
> numerical values [which may be represented by an algorithm]" (i.e. a
> Quantity).

But if we want to describe a flux quantity, then I'm with Ed an Brian,
since if I want to reuse a flux as given in a publication I will
have to trust the RA and DEC given by the author, and will have no access
to any pixel index. (And not all instruments are "pixel-based", like
photomultipliers, or bolometers of the first generation, but you would claim
that those are simply single pixel detectors).

Alberto