Re: [PATCH] initdb: map Windows' new Canadian time zone names

David Rowley <dgrowleyml(at)gmail(dot)com> writes:
> On Tue, 20 Oct 2026 at 14:34, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I also notice that the win32tzlist.out file that David sent has
>> differences that seem to amount to comment-line differences, but
>> I'm not really sure where that data is coming from on the Windows
>> side.

> Assume that's what you meant?

No, I was a bit mystified by these printouts:

Timezone Central Asia Standard Time changed displayname ('(UTC+06:00) Bishkek' from '(UTC+06:00) Astana')!
Timezone Greenland Standard Time changed displayname ('(UTC-02:00) Greenland' from '(UTC-03:00) Greenland')!
Timezone Greenwich Standard Time changed displayname ('(UTC+00:00) Monrovia, Reykjavik' from 'Windows uses this zone name in various places that lie near the prime meridian, but are not in the UK. However, most people probably think that "Greenwich" means UK civil time, or maybe even straight-up UTC. Atlantic/Reykjavik is a decent match for that interpretation because Iceland hasn't observed DST since 1968. / / (UTC+00:00) Monrovia, Reykjavik')!
Timezone Jerusalem Standard Time changed displayname ('(UTC+02:00) Jerusalem' from '(UTC+02:00) Jerusalem (old spelling of zone name)')!
Timezone Jordan Standard Time changed displayname ('(UTC+03:00) Amman' from '(UTC+02:00) Amman')!
Timezone Morocco Standard Time changed displayname ('(UTC+00:00) Casablanca' from '(UTC+01:00) Casablanca')!
Timezone Mountain Standard Time (Mexico) changed displayname ('(UTC-07:00) La Paz, Mazatlan' from '(UTC-07:00) Chihuahua, La Paz, Mazatlan')!
Timezone Paraguay Standard Time changed displayname ('(UTC-03:00) Asuncion' from '(UTC-04:00) Asuncion')!
Timezone Qyzylorda Standard Time changed displayname ('(UTC+05:00) Astana' from '(UTC+05:00) Qyzylorda')!
Timezone Syria Standard Time changed displayname ('(UTC+03:00) Damascus' from '(UTC+02:00) Damascus')!
Timezone Volgograd Standard Time changed displayname ('(UTC+03:00) Volgograd' from '(UTC+04:00) Volgograd')!

The report for Greenwich Standard Time is probably explainable by our
having this commentary in findtimezone.c:

/*
* Windows uses this zone name in various places that lie near the
* prime meridian, but are not in the UK. However, most people
* probably think that "Greenwich" means UK civil time, or maybe even
* straight-up UTC. Atlantic/Reykjavik is a decent match for that
* interpretation because Iceland hasn't observed DST since 1968.
*/
/* (UTC+00:00) Monrovia, Reykjavik */

and the Jerusalem report also visibly traces to our own commentary.
But the ones where the claimed UTC offset changes don't appear to me
to match up to anything.

Also, win32tzlist.out suggests adding this:

{
/* (UTC-05:00) Turks and Caicos */
"Turks and Caicos Standard Time", "Turks and Caicos Daylight Time",
"FIXME"
},

but that's nowhere to be seen in CLDR so I'm hesitant to do it.

regards, tom lane