[tz] Ambiguous abbreviations for Australian timezones when daylight savings is in affect

Russ Allbery rra at stanford.edu
Tue Apr 2 17:08:12 UTC 2013

Mark Davis ☕ <mark at macchiato.com> writes:

> That works for single points in time. It does not, however, handle
> repeating meetings. For example:

>   Mondays at 8:00 PT

If you're writing calendaring software, generally you switch to using
something like the tz identifiers, which give you America/Los_Angeles and
well-defined behavior.

You *definitely* do not want to use time zone abbreviations for this,
since they too would be completely wrong for the same reason!  If you
schedule a meeting in PDT, you want it to change to PST when daylight
saving time ends.  Which is the behavior you get from America/Los_Angeles
(or some equivalent identifier such as PST8PDT).

Humans don't need the abbreviation and don't care.  They either schedule
the meeting in local time or in the current time in some other time zone
(or possibly in UTC) and then just expect the software to cope with
changes due to daylight saving time.  This is a detail of the calendar
exchange format and internal representation, not the user interface.

Russ Allbery (rra at stanford.edu)             <http://www.eyrie.org/~eagle/>

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