[iaufwg] Registering the FOREIGN extension name

[Lucio Chiappetti]

On Wed, 4 Oct 2006, William Pence wrote:

> I was recently notified by Rob Seaman that the IRAF Group at KPNO has for a 
> number of years been using a FITS extension type that is not on the list of 
> extension names that are registered with the IAU-FWG.  This extension type 
> begins with the keyword XTENSION = 'FOREIGN '.  This is the same convention 
> that has been submitted to the Registry of FITS conventions and is now in 
> the 'Public Comment' period on the FITSBITS email list.

I find today the time to look at the FOREIGN extension, which I've been 
following on fitsbits (one of my doubts was that, dealing with an 
extension and not just a convention, it was more a matter of IAU-FWG and 
standard than of the convention registry ...), and now comes the two 
messages to IAU-FWG. Perhaps we should FIRST sort the issue at 
"convention" registry level, and THEN proceed to the next step in the 
"extension" registry ?

> I also plan to make 2 changes to the description of the 'Status' parameter 
> at the bottom of that web page:

I share the feeling of Steve Allen, that the procedure to register and 
approve a conforming extension is not well defined. Actually I was unaware 
of http://fits.gsfc.nasa.gov/xtension.html and of some of its content (the 
R items). I remembered well the two L items, which were the predecessors 
of IMAGE and BINTABLE, and in general felt that an extension was 
"something more than a mere convention".
 
> 1. delete the 'D' status (Draft proposal to be discussed in local FITS 
> commitees) because this status value has never been used and is unlikely to 
> be used in the future.
 
We should however specify a path to lead from L and/or R status to S 
status (which is OUR business).

> 2.  Create a 'C' status, which means "A conforming FITS extension that has 
> been in actual use and has not been elevated by the IAU FITS Working Group 
> to the status of a Standard extension".  The FOREIGN extension will be given 
> this status.
 
I do not see any reason why the FOREIGN extension cannot have the L 
status, maybe re-wording the explanation of this status (dropping the 
reference to "limited" ?) The description you give in the first lines I 
quote in this message (and also part of the document supplied to the 
convention registry) makes me think of something which is "local" i.e. 
"used in a particular site or within a particular community".

Or if you prefer merge existing L and your C into an A (Active) status.
So we'd have only three cases : non-standard extensions used somewhere, 
non-standard extensions with just a name, standard extensions.

I will now try to continue the specific discussion on FOREIGN on fitsbits.

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