proposed-features.txt

This is a list of headers that have been proposed but that were not
accepted *so far*.  If adopters have requirements like this, let the
editors know (at datacp at ivoa.net).  It's rather likely that we would
extend the set of headers accordingly.

(1) Computed FWHM (in Group 4)

The problem here is the definition given frequently rather imperfect
optics and a highly non-linear detector.  But if someone were to define
this properly, that would certainly be a valuable addition


(2) Markup for extra series

This is where people have plates with multiple numbers, e.g.,
observatory number and CdC numbers, or a "Halley plate set" with an
independent numbering, or the Wolf-Palisa plates taken at the Bruce
refractor.

It would be nice if we could give these alternative identifiers.  This
could be using SERIES1 SERIES2... and then PLATENO1, PLATENO2...  But
it's unclear at this point if that is worth the effort.  Perhaps just an
ALT-ID header containing free text is enough?  Will such a thing ever
need to be looked at by a machine?


(3) Extra computed metadata

In group 4, to make it easier to assess what a plate may be like, adding
AIRMASS, HA (hour angle), and ZD (zenith distance) at the mean epoch
(of the main observation?) might be useful.