gzipped images in SIAP 1.0

[Roy Williams]

> I understand that point, and I agree it makes sense in human terms
> to view a tile-compressed FITS file as an image.  However the point
> of registering MIME types is to standardize how applications are 
> supposed to treat streams of bytes that come labelled with particular
> MIME types. 

It seems to me that the problem is not with the MIME labeling, but with 
the undocumented plasticity of FITS. You can use a FITS file for a radio 
data cube or for a table of the Kings and Queens of England. I don't 
think we can expect the MIME type to cover all that complexity.

When a machine client reads a FITS file, it needs is a way to scan the 
FITS header and understand what it is and how to read it. I think the 
need "FITS types" that the VO can register.

Suppose each FITS file has a special keyword IVORN, whose value is a 
registry call number (ivo://...) that defines a "local FITS type". When 
we dereference the IVORN, we get the metadata:

-- Special keywords and their meaning (eg this comes from the Pink 
Galaxy Survey pipeline version 1.2).

-- Which interfaces are implemented (eg. this is a tile-compressed image 
+ this has the WCS keywords, this is a table of Monarchs).

-- What is the calibration model.

-- Services that can take a Pink Galaxy Survey file and give you the 
darks and flats and weather report and seeing etc etc

Roy