FW: Australian Timezone issues.

Robert Elz kre at munnari.OZ.AU
Tue May 11 07:06:26 UTC 1999

    Date:        Mon, 10 May 1999 12:38:43 -0400
    From:        "Olson, Arthur David (NCI)" <olsona at dc37a.nci.nih.gov>
    Message-ID:  <43E124CC389ED111B18D00805FEA1E63BC4D2C at nihexchange2.nih.gov>

  | Has any thought been given to having the Australian EST timezone renamed
  | to AEST?

No.   Or at least, I certainly hope it has not.

  | AEST is the proper abbreviation anyway in an international context

According to whom?   And then what would be the "proper" abbreviation for
the North American EST in an international context?

  | and is reported on international radio broadcasts that refer to
  | Australian timezones.

Yes, it would be, as do other countries long distance radio report
longer time zone names than they use locally.

  | For example, when a database dumps a time 'Sun May  9 11:07:06
  | EST 1999 in Australia, and then the database reads the time back in, it
  | assumes that EST is New York time and everything gets screwed up.

Any code that does that is simply broken.   Time zone names are a hint to
humans.  They simply aren't unambiguous.  The two Aust zone abbreviations
that are the same as their US equivalents (EST and CST) aren't the only
ambiguous ones around (and then there are all the places that have no
real concept of a timezone name at all - and the tz database just invents
one for them - most of the countries in South East Asia are given "ICT",
which seems to be "Indo China Time" which, as a label, means nothing locally
at all).

  | But typing TZ=EST date

This is a historical anomaly, it is retained for compatability only
(and even then, that particular example isn't very compatible with anything,
a traditional timezone string would have also had time offsets in it).

  | This means that a lot of UNIX software simply doesn't work properly in
  | Australia.

Only if it is broken.

  | Frankly I count the standard UNIX date program amoungst the
  | many because the time it reports as EST is different to the date it
  | reports when TZ=EST.

You give ambiguous input, you can expect to get ambiguous ouput.
If you want to specify Australian time, use TZ=Australia/Sydney or
whatever, and for North American, use TZ=America/New_York.  You need to
be more precise than just "eastern" anyway to represent historical times

  | What would have to be done to get this changed in the zoneinfo files?

First get the relevant four Australian states to change their time
legislation (or at least the one which most bothers you), so they
label the time zone "Australian Eastern Standard Time" instead of
just "Eastern Standard Time" (and in fact "Eastern Summer Time" which
also gives EST as its abbreviation).

Then it would make sense to change it.

Alternatively, convince the whole world that time zone names ought always
have a country, or region prefix - perhaps we could have "American Eastern
Standard Time" (not US, as it applies in Canada, and perhaps parts of
Mexico and other parts of Central America as well) and Australian Eastern
Standard Time, and both could be AEST ...

Time zone names are just an inherantly local phenomenon - anything, anywhere,
which intends to write, and then parse, a date string needs to be sure that
the string contains the numeric zone offset (or is simply written in UTC and
doesn't bother with zone information at all).


More information about the tz mailing list