[fitsbits] reopening of Public Comment Period on the Green Bank convention

[Demitri Muna]

On Jun 1, 2016, at 5:39 AM, THIERRY FORVEILLE <thierry.forveille at univ-grenoble-alpes.fr> wrote:

> Like Tom, I object to what seems to have become an implicit assumption that
> incorporating a convention into the standard is a good thing, as long as it
> has significant existing use. There are costs to extending the standard (unless,
> as Tom also says, one accepts that everybody uses cfitsio), and those need to
> be balanced against the benefits.  

I think this is an important distinction. There is a significant difference between documenting use of the FITS format and incorporating it into the standard. As an example, I recently came across UV data, which immediately crashed my FITS viewer, and then this in the AIPS File Format Memo:
> In the UV-tables form, the visibility data are written as a FITS binary table, normally placed after the other table extensions. The primary HDU has an AIPS conventional form meant primarily to be so odd as to act as a reliable identifier. The primary HDU asserts that the primary data has two axes, the first of which has 777777701 values while the second has zero values. This is sufficient to tell all FITS readers that the primary data set is not a random groups data set and otherwise contains no data. 
> 

This may be convention, but it's *lying*. I'm sure that there are untold numbers of FITS files of UV data that use this convention. Should it be part of the standard? Absolutely not.

The difference here is one of documenting use cases and *endorsing* the behavior for the future. As an application writer I need to know how people (ab)use the FITS format, but that doesn't mean that misuse should be endorsed because people are doing it. What would be useful for software writers is a document of use cases so programs like mine don't crash, but as a standards body the responsibility is to promote the best possible use of the format.

Cheers,
Demitri

_________________________________________
Demitri Muna
http://muna.com <http://muna.com/>

Department of Astronomy
An Ohio State University

My Projects:
http://nightlightapp.io <http://nightlightapp.io/>
http://trillianverse.org <http://trillianverse.org/>
http://scicoder.org <http://scicoder.org/>




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