[fitswcs] WCS with NAXIS=0

[Perry Greenfield]

Eric Greisen wrote:
> Perry Greenfield wrote:
 
>  >   to specify the highest value of the index of any WCS keyword in
>  >   the header (i.e. CRPIXi, PCi_j or CDi_j, CDELTi, CTYPEi, CRVALi,
>  >   or CUNITi). The default value is the larger of NAXIS and the
>  >   largest index of these keywords found in the FITS header...
> 
>       I do not see how this is ambiguous.  No WCS keyword may have an
> index in excess of WCSAXES and its default in this case is the highest
> value in the header.  This allows anything - which is why neither Mark
> nor I liked WCSAXES in the first place.
> 
No, I didn't think it was ambiguous, but I wondered how it implied
that having that happen was illegal which is what was being asked.
After all, FVERIFY needs to distinguish legality from style (or should
at some level)

>       And my reply to Bill just now is one of style not legality.  Any
> use of WCS that purports to be "modern" in the sense of Papers I, II,
> and III and depends on defaults and fails to provide WCSAXES while
> using axes > NAXIS is extremely unprofessional.
> 
I'd say that your reply to 

>> Should this be considered an error if there is no WCSAXES keyword?

>Yes

could be taken to mean that it was illegal, not just bad style,
so I'm glad you cleared this up. I also agree that it would be
better to have WCSAXES. The usage being discussed are for files
several years old now so it's not a question of whether this
is being considered for new datasets.

Thanks, Perry