VOUnits 1.1 RFC

[Norman Gray]

Greetings

I'm following up Steve's remark on the Interop list; Markus has suggested that subsequent followups happen on the Semantics list.

On Tue, Jul 04, 2023 at 10:22:07AM -0700, Steve Allen wrote:

> On Fri 2023-06-30T17:59:38+0200 Markus Demleitner hath writ:
>
>> * Clarified: that Besselian year is not in FITS.
>
> I am mystified at this change.

I think the problem here is a combination of a poor change-note and possibly my misinterpretation of a remark from Arnold.

The VOUnits document was changed in April 2022 [1] to note that FITS4 states that use of the besselian and tropical years ‘is not encouraged’ (I note that there were a number of only peripherally related tweaks in that commit -- I reproach myself for deplorably poor VCS discipline).

Previous to that (October 2014 [2]), in the Unity library (a table from which is incorporated into this VOUnits document), I edited the list of ‘known units’ to remove the besselian and tropical years from the list of units recognised by FITS (column 3 in known-units.csv).  I think they sprang from a comment by Arnold [3], which I possibly interpreted in two different ways in 2014 and 2022.

Thus, I think these two changes are not consistent with each other.  It sounds, from Steve's remark, that the best thing would be to revert the 2014 change and list Ba and ta as 'recognised but deprecated' in the FITS column.  Would anyone care to make a Ruling?

Best wishes,

Norman


[1] https://github.com/ivoa-std/VOUnits/commit/7108c1f9943f76f2ac7960a6d853ec36673ea404
[2] https://heptapod.host/nxg/unity/-/commit/b45b533ada39f44e04540ef6372eab67a6827f61
[3] http://mail.ivoa.net/pipermail/semantics/2013-July/002397.html

-- 
Norman Gray  :  https://nxg.me.uk
SUPA School of Physics and Astronomy, University of Glasgow, UK