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

Timothy Arceri t.arceri at bom.gov.au
Thu Mar 28 02:33:24 UTC 2013

Hi All,

I’d like to bring this very important issue back up for discussion. I’m going to
attempt to address the reason why this change is needed as clearly as possible
while addressing the concerns from previous discussions. The issue is with both
EST (Tasmania, Victoria, New South Wales, Queensland) and CST (South Australia,
Northern Territory)

It's well past time the Australian abbreviations were updated to reflect the
current terms and usage. Stop the confusion and use the abbreviations
recommended by the Australian government to try to avoid this mess.


As others have posted I’m not too concerned about the 'A' but as you will see
differentiating between daylight savings times is extremely important when you
are using this information in a system that crosses state boundaries and in our
case an emergency warning system.

Previous Post:
“I'm not a big fan of change for change's sake; once the database is one way I
like to leave it alone.  For phrases, the new statistics seem to be quite
strong; for whatever reason, Australians seem to be voting with their feet (or
fingers) and are adopting American terminology with an "Australian", when the
time zone names are spelled out.  For abbreviations, it's not clear whether
"AEDT" or "EDT" is more common, though I suppose "AEDT" has a slight edge.

I'd like to hear more from Australian correspondents on this before thinking
about specific changes, though.” - Paul Eggert (26 Aug 2008)

I don’t think anyone here cares deeply enough about time zone abbreviations
enough to be arguing about change for change’s sake. The fact is the ambiguity
of the current abbreviations for time zones is causing real world problems.  
Previous Post:
“Alphabetic time zone abbreviations should not be used as unique identifiers for
UTC offsets as they are ambiguous in practice.  For example, "EST" denotes 5
hours behind UTC in English-speaking North America, but it denotes 10 or 11
hours ahead of UTC in Australia; and French-speaking North Americans prefer
"HNE" to "EST".” - Paul Eggert (26 Aug 2008) 

The issue is not that the identifiers are not unique worldwide. The problem is
that they are not unique to bordering states in the same country which run along
the same time zone. Most apply daylight savings time, one (Queensland) does not,
this is what causes the confusion. Simply using UTC +10 or UTC +11 is not good
enough as the general public has no idea what UTC is. 

Previous Post:
“I have always assumed that the common abbreviation (EST for standard time, and
EST for summer time) was a very deliberate choice, chosen so that if it ever was
appropriate to specify a time with an abbreviated zone name, then the time
specified would apply year around, which is almost always what is intended” -
Robert Elz (5 Jan 2009)

If all states that used EST applied daylight saving then this would be
convenient but as stated above they do not. The problem can be seen in the
delivery example where it would appear an Australian company does delivery’s via
time travel.

Previous Post:
“Queensland don't have Daylight Saving Time. New South Wales (across the border
from Queensland) do have Daylight Saving Time. Due to the fact that the Olsen
data uses EST for both 'Eastern Summer Time' (New South Wales)  and 'Eastern
Standard Time' (Queensland), a delivery from New South Wales to Queensland  can
have a pickup time of 10.30am EST and a delivery time of 10.00am EST. We like to
be efficient but we're not that good. System users only see the EST and get
horribly confused.” - Mick Johnston (26 Aug 2008)

So obviously I’m pushing this for my own reason also. We currently use unix
based systems to produce tsunami arrival times for the Australian Tsunami
Warning System. This information is displayed on a public webpage (and as
described above cannot use UTC convention). The issue comes into play when
listing arrival times for the east coast of Australia, simply listing all
arrival times as EST will obviously cause confusion especially for towns located
near the border of NSW/QLD where it would appear to take a tsunami an extra hour
to arrive only a couple of kilometres away.

Currently we cannot use the default unix time zone commands and must rely on the
use of a script to parse the time zone files and produce EST/EDT abbreviations.
Obviously the ideal solution is to fix the EST/CST abbreviations once and for
all so the all Australians can finally have software that produces time zones
abbreviations that can be read by the general public and be used without having
to provide added context.

Note: In our organisation alone this issue has been brought up independently by
multiple areas.

Timothy Arceri

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