[tz] tzdb timezone names/identifiers and links

Tony Finch dot at dotat.at
Tue Feb 26 18:17:06 UTC 2019

Guy Harris <guy at alum.mit.edu> wrote:
> And I'm not even convinced that users want to care about tzdb regions;
> those regions don't completely correspond to, for example, what people
> call "time zones" in the US, so "Mountain time" or "Mountain time zone"
> doesn't correspond to the America/Denver tzdb region - Arizona is in the
> "Mountain" time zone, but it hasn't done standard/summar time switching
> since 1968, unlike other parts of that time zone.
> What I suspect users want is to have clock time work appropriately for
> their location; if doing so doesn't involve knowing or caring about the
> details of the tzdb, so much the better.

Up to a point...

A common cause of significant confusion is when people are trying to
organize meetings between people in multiple time zones. I think the
confusion is due to poor calendaring data models which make it difficult
to provide a user interface that illustrates what is going on.

(old long version of these thoughts: https://fanf.livejournal.com/104586.html)

The key point is to attach one or more locations to an event. The system
needs to be able to look up which timezone applies to which locations;
there are ways to make that easyq. One of the locations is the primary
location, and the event's scheduled time is local time at that location;
the secondary locations allow users to easily see what time it is for all
the participants, so they don't accidentally schedule something for 05:00.
And it allows the system to automatically flag up weirdnesses that happen
in March or October or when TZs change. In particular it's easy to find
out when TZ changes have effects that matter to meeting schedules without
false positives. And if the primary UI is location, not TZ, there's less
likelihood of idiocies like Microsoft Exchange saying the time in
Cambridge in July is GMT.

f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/
Northwest Hebrides, Southeast Bailey: Southwesterly becoming cyclonic, 4 or 5.
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