FITS Serialization Questions for SSAP 0.93

[Randall Thompson]

We are continuing to work on producing SSAP-compatible FITS files
for MAST and HST.  A  few questions came up in the process.

1) Most of our spectral FITS files have general parameters stored in the 
primary
 headers (e.g., DATE) and I was hoping to leave these intact when 
creating the new
versions. Does the SSAP require the specified keywords to appear in the 
extension
headers? Obviously some are required there.

2)  We have at least 3 missions containing echelle spectra. Typically 
each spectral
order has a different number of data points. I assume the recommended
way to store these would be as multiple rows in a binary table using 
variable length
arrays.  Is this correct? Do you recommend any format which would not 
require the
use of variable length arrays (other than writing them to separate 
files)? I was wondering
for example about using padded zeroes to store multiple orders in a 
single binary table,
or having multiple binary table extensions, one for each spectral order.

3) I know the SED data model paper is not yet complete, but it would be 
useful to
have more information on defining the listed FITS keywords (e.g., the 
curation and WCS
entries).

Randy