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

[Dick Shaw]

I think it is very useful to reserve the INHERIT keyword, as a great many FITS files that use this 
convention have been archived. I also agree that adding the proposed appendix gives INHERIT some 
useful visibility, and clarifies it's use. I suggest a minor re-wording of a couple of points in 
the proposed appendix:

1. Paragraph 1, add after sentence 1:

"The INHERIT keyword *must not* appear in the primary header."

2. Paragraph 3, sentence 3:
"The mandatory primary array keywords (e.g., BITPIX, NAXIS, and NAXISn) and any COMMENT, HISTORY, 
and blank keywords in the primary header are never inherited."

I believe "never" is not one of the official holy words (must, shall, may, etc.) per RFC 2119. I 
suggest the following modification:

"The mandatory primary array keywords (e.g., BITPIX, NAXIS, and NAXISn) and any COMMENT, HISTORY, 
and blank keywords in the primary header *must not* be inherited."

-Dick

On Wed, 08 Jun 2016 12:00:04 -0400
  fitsbits-request at listmgr.nrao.edu wrote:
> ----------------------------------------------------------------------
> Message: 1
> Date: Tue, 7 Jun 2016 18:50:59 +0200 (CEST)
> From: Lucio Chiappetti <lucio at lambrate.inaf.it>
> To: FITSBITS <fitsbits at nrao.edu>
> Subject: [fitsbits] reopening of Public Comment Period on the INHERIT convention
> 
> ANNOUNCEMENT:  START OF FORMAL PUBLIC COMMENT PERIOD
> 
> This is to announce the official reopening of a formal Public Comment 
> Period to reserve in the FITS Standard document a keyword (INHERIT) for 
> use by a registered convention (not part of the Standard)
> 
> A previous PCP was held in June-July (started on 19 Jun 2015).
> 
> We are now re-opening the Public Comment Period to report the situation 
> before passing to a vote to modify the standard document.
> 
> The so called header inheritance (for short INHERIT) convention allows to 
> specify whether keywords common to primary and extension HDUs can be 
> written only once in the primary HDU and inherited by the extensions.
> 
> During the previous PCP, contrasting opinions were expressed towards the 
> original proposal, which aimed to *incorporate* in the standard the 
> INHERIT convention. This was actually one of the more controversial 
> proposals during the recent PCPs.
> 
> Therefore we are NO LONGER proposing to promote the INHERIT convention 
> as part of the standard, but merely to recognize its existence as a 
> registered convention, and to reserve a single keyword for its support to 
> prevent future conflicts.
> 
> The proposed text consists of a couple of paragraphs (and a few words) 
> highlighted in brick red in section 4.4.2.6 as presented in first page 
> of the draft available at this link
> http://sax.iasf-milano.inaf.it/~lucio/FITS/Conventions/inherit-rev.pdf
> 
> The text contains also in the second page also an excerpt of Appendix H.3, 
> which now makes clear the INHERIT convention remains a registered 
> convention.
> 
> It contains as well in the third page a new Appendix K which provides a 
> brief description of the convention.
> 
> Please review the text carefully and post any comments, criticisms, or 
> suggestions on the FITSBITS mailing list.
> 
> Supporting material for the PREVIOUS public comment period announcement 
> can be retrieved from the FITSBITS archives starting from 
> https://listmgr.nrao.edu/pipermail/fitsbits/2015-June/002618.html
> ==================================================================
> 
> The reopened Public Comment Period starts today 07 June 2016 and will 
> last until 17 June 2016, unless extensions are requested and motivated.
> 
> -- 
> Lucio Chiappetti - INAF/IASF - via Bassini 15 - I-20133 Milano (Italy)
> for IAU FWG (prorogated)