[tz] Converting cities to tz identifiers (tangent)

Adam Vartanian flooey at google.com
Wed Feb 21 10:27:45 UTC 2018

> >> What is meant by "the US Eastern time zone"?
> >
> > I think the colloquial meaning applies. The case I'm thinking of would
> be things like a hotline which advertises its hours in "Eastern time"
> rather than the time zone of a specific city, or a distributed team
> following roughly US time zone rules that schedules their meetings in
> "Eastern time" even though the members of the team are in various locations.
> Fortunately, every US location in the Eastern time zone observes DST, so
> the city doesn't currently matter.
> But what happens if somebody decides to schedule a meeting in "Mountain
> time" some time between 2 o’clock antemeridian on the second Sunday of
> March and 2 o’clock antemeridian on the first Sunday of November?  That
> wouldn't suffice; you'd either have to explicitly schedule it for "Mountain
> standard time" or "Mountain daylight time", or treat it as implied that
> Arizona doesn't count and "Mountain time" is "Mountain daylight time"
> during that period.

In my experience, usage in everyday speech is generally that Arizona is
said to spend the winters in Mountain time and the summers in Pacific time,
rather than spending the whole year in Mountain standard time.  So if you
say "Mountain time" in the summer, people understand that to be UTC-6, even
when dealing with people in Arizona.

This is kind of fuzzy definition is insufficient for a project like tzdb,
but in a user interface it might well be the best understood option.

- Adam
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