[fitsbits] Primary & Alternate WCS Keyword Order

[Petr Kubánek]

> > In general, I think we should avoid as far as possible positional 
> > constraints on header keywords.
> 
> A major instrument being commissioned has randomly ordered keywords in each header, has randomly ordered HDUs, and submits sequentially acquired exposures in a random order to the archive.  Placing constraints on the key structural keywords is similar to requiring that the primary HDU be the first one in the file.  There may be higher order implications such as the inheritance issues you mentioned.
> 
> Rob

I fully agree on those statements. Usual FITS handling libraries allows
random access to headers, so order is not an issue. If somebody will
point me to stream oriented FITS library where the order matter, I will
be happy to change my mind.

Petr