[tz] tzdb timezone names/identifiers and links

Martin Burnicki martin.burnicki at meinberg.de
Tue Feb 26 08:42:49 UTC 2019

Brian Inglis wrote:
> On 2019-02-25 05:37, Tony Finch wrote:
>> Martin Burnicki <martin.burnicki at meinberg.de> wrote:
>>> For example, the zone "Europe/Macedonia" is displayed as
>>> "Europa/Makedonien" on my Linux/KDE system set to German language. As
>>> far as I can see each project that has to deal with this kind of things
>>> has to provide the translations by themselves.
>>> Since TZDB is maintained on github I'd expect there would be quite some
>>> folks that were happy to provide translations for zone names, eventually
>>> exported from their own, local projects.
>> I thought this kind of thing was done by the CLDR, though it seems to map
>> from TZ names to translated exemplar cities, which is slightly different
>> than a direct translation of the TZ name.
>>> Another point that has recently been discussed is how an event time is
>>> affected if the time zone rules change after the point in time where the
>>> event is created for some local time, and before the time the  event
>>> happens.
>> The way to deal with this is to assign the event a sensible primary
>> location, and do the mapping from location -> tz lazily on demand.
>> However the standard data model (iCalendar) doesn't allow this.

Yes, but as far as I have seen calendar apps often try to do the
conversion, more or less successfully.

For example, if I add a calendar event (e.g. using Thunderbird with
Lightning addon) for a time in a different time zone and synchronize my
phone via a caldav server then the displayed event time changes
depending on the zone I'm currently in, or I've currently configured.

This is expected, but if I edit the event then my phone may display a
different zone name for the start/end times than Thunderbird's
lightning, so a pure user may see that the current UTC offset is as
expected, but he doesn't even know if the DST rules are the same for
both displayed settings, or if they refer to different zones which
accidentally have the same current UTC offset.

> The sensible locations would be major cities and towns in each country's time
> zones. To support this apps need a common gazetteer to map from major cities and
> towns to tzids.

Yes, that's exactly what I meant.

> GeoNames.org data provides timezones for many locations, is used by many orgs,
> and is a good base if the CC BY 4 licence conditions are acceptable
> https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0
> License. Forums and mailing lists are hosted on Google groups.

Thanks for the pointer.

> Pareto principle applies here, as most people in most countries currently use a
> single time zone, so a location mapping to a country defines their observed time
> zone; minorities observe different time zones for business, colonial, cultural,
> economic, geographic, historical, or social reasons; some countries, mainly in
> the Americas, require more than a single time zone because they spread widely
> across longitudes, with additional time zone variations because of the above
> differences; these countries and minorities need better mappings.

Martin Burnicki

Senior Software Engineer

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