general comments to SSAP and SDM from outside

[Doug Tody]

Hi Jonathan -

On Mon, 27 Aug 2007, Jonathan McDowell wrote:
> Doug, I am against reusing the background model element in this
> way - the semantics are different as well as the (subtract vs divide) issue.
> I think it would lead to confusion and defining a subtype of 
> 'spectral association' is a better way to go, since we are going to be
> having these spectral associations.
>  - Jonathan

I think the main thing is that the document cover how to represent
a normalized spectrum, which it does now, so I can agree with this.
The only thing is that in many cases (e.g., a continuum normalized
spectrum) I suspect the normalization function was computed from the
data, hence there is as much argument to include it in the dataset
as there is for including the background model (indeed, in some cases
they may be the same).

The association technique will work too (this is already in SSA),
however once the dataset has been retrieved, if the query response
is no longer available, the information about how to retrieve the
normalization spectrum is no longer readily available.  But it
is probably of interest only in the context of a single spectrum,
unlike the more normal case of association where we are describing
some more complex object or set of available views.

What we have is probably sufficient for now, especially since I
suspect people working with normalized spectra often don't look at
the normalization function in any case.  Hence, unless others object,
it is fine with me to leave go with what we have now and leave this
to be resolved in a future version.

	- Doug