bug#81420: GNU Calc time zone issues in western Canada etc.

Paul Eggert [23/Jul 11:41am -07] wrote:
> On 2026-07-23 03:44, Sean Whitton wrote:
>> What opinion do you have on whether we should follow the RFC (modulo
>> issues raised by Eli)?
>
> I'd be inclined leave things pretty much as-is on the Emacs master
> branch, which follows RFC 5322's lead and declares abbreviations like
> "PST" obsolete and accepts them only for historical reasons.
>
> Although the "PST" abbreviation might change its popular meaning from
> -08 to -07 in British Columbia, or even in the US if the Sunshine
> Protection Act becomes law[1], it would surely take some time for that
> to happen and in the meantime there will be confusion no matter what GNU
> Calc does. In situations like these it's often better to stand pat.
>
> I did another quick pass over the Emacs doc looking for problems in this
> area and installed the attached into the Emacs master branch to fix what
> I found. This affects areas other than GNU Calc.
>
> In TZDB, which has the problem of *generating* abbreviations, I'm
> becoming inclined[2] to follow Robert Elz's suggestion if the Sunshine
> Protection Act becomes law, so that low-level C functions like localtime
> and shell commands like "date" and Emacs functions like
> current-time-zone will say "-07" rather than "PST" or "PDT". "PST" would
> be confusing (-08 or -07?), and "PDT" would incorrectly imply daylight
> saving time when it is in fact standard time.

This makes sense to me, thank you for working on this.

-- 
Sean Whitton