[tz] RES: Timezone for Brazil

Doug Ewell doug at ewellic.org
Tue Oct 10 21:23:53 UTC 2023

Paul Eggert wrote:

> On 10/9/23 17:45, Fabrício Rennó via tz wrote:
>> As I've mentioned in my initial e-mail, Brazil officially has 4 time
>> zones (-2, -3, -4, -5), therefore for anything time/schedule related
>> in Brazil a person should opt among only those 4 time zones options.
> On my long list of things to do is coming up with a table that would
> let users do that more easily. It would be like tzdb's current
> zone1970.tab, which partitions the world into zones where clocks have
> agreed since 1970; however, it would partition the world into a
> smaller set of larger zones whose clocks agree now and are predicted
> to agree in the future.
> This would be something along thne lines as you suggested, as people
> in Brazil would have just four zones to chose from in this new table.

This would be very helpful for applications like ours, which asks users to select a time zone which is then transmitted to an external device that requires a tzid. Thanks to CLDR, the user gets to choose a human-readable name instead of a raw tzid, but still has to choose from among many time zones with the same base offset.

Only current and future timestamps are relevant for this app and these devices, so (using Guy’s example, which is also in my home TZ) it would be appropriate for U.S. users to pick America/Denver or America/Phoenix—again, converted to a CLDR name, with city “hints”—and not appropriate to pick America/Boise or America/Edmonton or any of the other UTC–7 zones.

Remember that most users are not as knowledgeable about time zones as we are. In an informal poll of co-workers about the list of ~425 zones, some thought they should pick the zone corresponding to the city physically closest to them, e.g. America/Detroit in preference to America/New_York.

It would be great to cut down the list exactly as Fabricio and Paul describe, but we obviously didn’t want to build that list ourselves only to become responsible for maintaining it down the road.

Doug Ewell, CC, ALB | Lakewood, CO, US | ewellic.org

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