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Re: How to tell (in advance) if a date-time is ambiguous?

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July 11, 2017 08:08
Re: How to tell (in advance) if a date-time is ambiguous?
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On 10.07.2017 20:14, Eric Brine wrote:
> I don't understand the conditions. The law determines when the switching
> of offsets from UTC happen, not some person. The switch doesn't happen
> at 08:48:27 am in Chicago; it happens at 2am.

This point of view is a bit U.S. centric. Indeed, you are describing how
it *should* be, but

1) The timezone database is updated several times a year, and that
surely has its reason. Obviously, laws are changing (a part of them very
surprisingly and fast), and the next law could determine the switch to
happen at 08:48:27 am, and

2) Laws are made by persons, in some cases by a single person. For
example, in 2007, Venezuela's president Hugo Chavez moved Venezuela's
time zone by 30 minutes backwards without any real reason, but just as a
political statement, putting the country in a half-hour time zone. This
shows that weird things can happen to time zones at all times and very

(Note: Venezuela has been in that time zone for about 9 years and now is
back in UTC-4:00, but that does nothing to business here).

Thus, when developing an application targeted to audience all over the
world, you can't rely on what you know about your own country.

Thank you very much,


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