Acronyms for Australian Time Zone Seasons

Sean B. Durkin sean at
Wed Jan 24 03:06:23 UTC 2007


I wish to reopen the debate about the Australian Time Zone acronyms
(EST versus AEST versus EDT versus AEDT).

In the TZ database, the acronyms for the "Australian Eastern Standard Time"/
"Australian Eastern Daylight-Saving Time" time zone seasons is given as 
It is similar the for Central Time and Western Time (CST/CST and WST/WST
respectively. The source file for australia discusses the case for these 
and also the case for alternative acronyms:

  (a) EST/EDT; and
  (b) AEST/AEDT.

It looks like Mr.Olsen has settled on EST/EST because there is no 
support for any official acronyms, and EST/EST is the most widely used.

Within the source file, the Bureau of Meterology's web page on the subject
("") was 
in passing, however not any more was said of it. I believe that this web
page should be given more weight than it has been given. This page
shows that the Bureau of Meterology uses EST/EDT rather than EST/EST.

Given a perusal of all the other web pages mentioned in the source file,
I believe that this page represents the closest thing we can get to an
"official" set of acronyms.

I would like to make the case for using AEST/AEDT as the acronyms. Here are
some points to consider, which have not been noted in the source file.

Even when the context of Australia is know, EST/EST makes it impractical
to record times in the local clock with the acronym.
For example in an event is recorded in the Australia/Sydney time zone as
"2-Apr-2006 02:30 EST", and the context of "Australia" is given, what 
does this
mean? It is ambiguous. It could be taken to mean either:
  (a) 1-Apr-2006 15:30 GMT; or
  (b) 1-Apr-2006 16:30 GMT.
I suggest that it would be better to have a pair of acronyms that could
be used to differentiate standard time from daylight saving time.
I acknowledge that there has already been considerable discussion on
the relative importance of having unambiguous acronyms, but that was in the
wider context of all time-zones. The point that I am trying to make here
is the advantage of unambiguous acronyms just in the case where the time
zone is already known as Australia/Sydney.

To be consistent with the treatment of other timezones, we should go
with the closest thing to the official acronym, rather than the most popular
one. I acknowledge that there is no legislatively official acronyms, but
a mentioned earlier, the Bureau of Meterology's usage of EST/EDT is close.
However the Bureaus' intended readership is Australian readers. It is not
too hard to extrapolate from their full spelling of the seasons
"Australian Eastern Standard Time" and "Australian Eastern Daylight Time",
that had their audience been more international, that they would have 
the obvious acronyms AEST and AEDT.

I respectfully propose using AEST/AEDT, ACST/ACDT and AWST/AWDT as acronyms
for the respective Australian time zones within the TZ database.

Sean B. Durkin

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