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

Timothy Arceri t.arceri at bom.gov.au
Thu Apr 4 04:32:13 UTC 2013

Paul Eggert <eggert <at> cs.ucla.edu> writes:

Despite every man and his dog giving requirements for what needs to be
proven for this change to be made it seems like Paul Eggert is the only one
who can tell me for sure what the requirements for change are. 

I have already been accused of cherry picking government websites. When in
fact all I did was point out the timezone information located on each state
government website. Then for the couple that didn’t have a dedicated page
with that information I searched the website for a timezone abbreviations. I
chose to locate these webpages not as a cherry picking exercise but due to
the objections to the use of the timezones on the Australian government
website, where it was argued that it was an individual state issue.

>Paul Eggert:
>>>> No ii says “Daylight saving or summer time is commonly expressed as EDST”.
>This is splitting hairs, surely.  That page uses two different 
>abbreviations, AEDT and EDST, for the same notion.  It doesn't say that 
>one abbreviation is preferable to the other.”

No this is not splitting hairs. Yes I agree it could have been worded a
little bit clearer but it is obvious to anyone that is not arguing against
having to change the Olson database that EDST is just provided as a
reference for those who have come across this abbreviation somewhere else.
The Northern Territory website does a better job of making the point that
the abbreviation on the Australian government website are preferred while
still providing the other common expression as a reference.

“The Time Zone in the Northern Territory is Australian Central Standard Time
(ACST, also commonly referred to as CST).” -

Regardless you have ignored the fact that none of them use EST abbreviation
for daylight savings as is used currently in the database.

>Paul Eggert:

>“We shouldn't try to address this problem by choosing a preferred set of
>abbreviations and then finding web pages agreeing with our preferences.
>Instead, we should choose what Australians by and large use in practice.
>Unfortunately, when I recently tried to do that
>I found that the practice seems to be inconsistent: that is,
>in some regions Australians seem to prefer one set of abbreviations,
>while in other regions they seem to prefer a different set.”

Again this does not address my main concern that regardless if states are
using AEST/AEDT vs EST/EDT that EST is not commonly used as abbreviation to
denote daylight savings time.

I would also like to point out some major flaws is your use of searches to
gauge what Australians prefer to use rather than using the suggestions of
the Australian government or its state governments.

1. A large number of the timezone abbreviations used in webpages are placed
there using an automated process, such as page last updated times. On a Unix
based server where customisations have not been made to output AEST, etc you
are going to be getting the abbreviations from this very database.

2. Searching for three letter abbreviations is going to bring back a far
greater amount of false positives. All you need to do is look at the first
couple of pages of google results to see how bad this is.
For example search for "WST" site:.au On the very first page half the result
are for Workplace Standards Tasmania (WST). On page two there is only two
result that are related to timezones, there results for water meters, the
west tigers (WST) national rugby team and stock market codes further pages
continue with the same false positives. The results for CST, and EST also
show similar false positives with both first pages not returning a single
result to do with timezones. 
On the other hand the four letter abbreviations do return some false
positive but to a far lesser extent.
If you take the ratio of the false positives into account it starts to make
your results from last October look much more favourable on the Australian
Government defined abbreviations.

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