[tz] What data should TZDB offer?

Stephen Colebourne scolebourne at joda.org
Mon Jun 7 15:42:24 UTC 2021

On Mon, 7 Jun 2021 at 16:12, Fred Gleason via tz <tz at iana.org> wrote:
> On Jun 7, 2021, at 10:53, Stephen Colebourne via tz <tz at iana.org> wrote:
> "what people in a region think" is essentially unknowable. What
> governmental authorities define is generally well recorded. Where we
> can accurately fnd data to indicate that a region is not following the
> lead of the governmental authorities then I agree we need to make sure
> that those people's experience can be expressed in some form by TZDB.
> But I think that governmental authorities so dominate the field of
> timezones, and what our downstream users perceive of timezones, that
> we need to reflect it. Putting our heads in the sand and pretending
> that governmental authorities don't exist is not helpful.
> Other than Asia/Urumqi, I’m hard pressed to call to mind a region where a significant section of the population has basically decided to defy all governmental authority. However, there are areas where *which* governmental authority is relevant is a very live question (the Crimea comes to mind immediately). The “what people in a region think” standard allows TZDB to avoid taking sides about which political entity is the “legitimate” one.

The proposal does not take sides about which political entity is the
“legitimate” one. I wouldn't want tzdb to do that.

Imagine a case where country A invades country B and takes control of
the city that TZDB references, but not the whole country, and then
imposes its own timezone in that city. With the current rules, TZDB
would update the current timezone rule for the city to that of the
invader's new rule, because that is what people in that city
experience. But for the rest of the country that was not invaded would
still need a region in TZDB to record it's current timezone. Thus a
new region would need to be created based on the largest city in the
remnants of the invaded country. With the new rules, the same process
would occur.

I contend that the new rule only really affects pre-1970 data, not how
TZDB approaches changes in geopolitics.

If the TZDB IDs were of the form Country/City, eg Germany/Berlin, I
would agree with the concern, but fortunately they are not.


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