[fitsbits] start of Public Comment Period on the INHERIT convention

[Rob Seaman]

On Jul 1, 2015, at 12:19 PM, Steve Allen <sla at ucolick.org> wrote:

> Whereas we are effectively relying on the conventions of the INHERIT
> keyword, we did not choose to use the INHERIT keyword.  The usage in
> the FITS files from DEIMOS, HIRES, and LRIS is sensible, legal, and
> not part of the FITS standard.  I do not object to making INHERIT part
> of the standard.  I also do not see the need to add the complexity of
> INHERIT to the FITS standard.

Isn’t it more a question of how to disinherit the primary header (should that ever prove necessary)?  For use cases in which an MEF represents a single (if perhaps, complicated) observation, it is only natural to regard the contents of a (dataless) primary HDU as pertaining to the observation as a whole and hence as being inherited.  How then would one assert the opposite other than by placing INHERIT=F in HDUs for which the primary doesn’t apply?

The question is whether disinheritance is something any project has ever needed.

That said, an important aspect of this exercise is to capture usage that already exists.  Large amounts of data have been written relying on INHERIT.  The keyword should be reserved for this purpose and whether in the standard or a style guide the usage should be described such that these pre-existing data files can be properly interpreted in the future.

Rob