FW: Australian Timezone issues.

Alex LIVINGSTON alex at agsm.edu.au
Tue May 11 04:42:45 UTC 1999

At 11:37 +1000 1999-05-11, Chris Bitmead wrote (quoting me):
>> On the other hand, I thought the tz database did not
>> attempt to specify unique time-zone abbreviations. (If only
>> all time references would be qualified simply by a UT
>> offset!)
>UT offsets don't work because of summer time rules. I thought that was
>the whole point of these abbreviated timezones "EST" is that this small
>3 letter token encompassed a whole lot of rules and historical data in a
>short abbrev.

Of course UT offsets work all the time! That's the whole point: specify the
one applicable at the time. Do you need to know the UT offset at any other
time than the instant being identified? Even time-zone abbreivations are
*usually* different if daylight-saving is in effect; do you think they
*should* be able to be the same for a certain geographic region regardless
of whether daylight saving is in force or not (like the north American
"ET", "PT", etc.)? The only circumstances I can think of when this would be
useful would be giving times of day without date specification (e.g.
business hours). But in such cases either "local" time can be assumed (and
no time-zone qualification is necessary) - when geographic location is
plain - or it should be made clear exactly what is meant by specifying UT
offsets and giving some indication, taking into consideration the likely
readership, of when each applies, e.g. "UT+10 from the Sunday nearest March
28 to the Saturday nearest October 27, UT+11 otherwise, at time of writing
(1999)" or "UT-04 when daylight-saving is in force in the US, UT-05
otherwise". Even the latter case doesn't cover all bases, as the time zone
of the locale is still subject to change (didn't Georgia recently decide to
switch zones?). For long-term accuracy (of geographically tied references),
specifying the relevant locale is the only way.

Macintosh and Lotus Notes Support / Information Technology (IT)
Australian Graduate School of Management (AGSM)
The University of New South Wales (UNSW) / [Sydney]  NSW  2052 / AUSTRALIA

E-mail   : alex at agsm.edu.au; cit at agsm.edu.au (IT)
Facsimile: +61 2 9931-9349 / Telephone: +61 2 9931-9264
Time     : UTC+11---[last Mar. Sun.---UTC+10---[last Oct. Sun.---UTC+11---

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