[Linux-aus] Western Australian Daylight savings

Glen Turner glen.turner at aarnet.edu.au
Fri Nov 24 12:02:03 UTC 2006

Andrew Donnellan wrote:

> Secondly I wonder when NIST or whoever controls tzdata will release a
> new version (which GNU has to take into glibc, distros have to
> integrate etc.)

Global time zones are not monitored by any standards organisation.

In Australia the federal government has Constitutional authority
for weights and measures, but have not used this power to set
time zones, leaving the states free to legislate within their

The people that invented the tz timezone system for UNIX maintain
a mailing list which tracks timezones as well as they can, which
you can view at
and an archive of tzdata at

The current of tzdata2006o does not incorporates the pending WA
change.  The legislation was poorly drafted, which makes
developing a rule to cover more than this year more complex than
it should be. It was also not clear if the law was yet in force;
due to past experiences tzdata prefers to track changes only when
they are fully official.

The poor attention of drafters to timezone issues isn't unique
to WA. Here in SA the timezones are "Central Standard Time" (CST)
and "Central Summer Time" (CST) and since the legislation or
National Measurement Institute don't define alternative abbreviations
the standard timezone is CST and the summer time is CST. Duh!

The current proposed patch for the tzdata australasia timezone file
revamps the Western Australia entry to

# Western Australia
# From Christopher Hunt (2006-11-21), after an advance warning
# from Jesper Norgaard Welen (2006-11-01):
# WA are trialing DST for three years.
# <http://www.parliament.wa.gov.au/parliament/bills.nsf/62D4F7C55EA88993482572110007316A/$File/Bill174-1.pdf>
# Rule  NAME    FROM    TO      TYPE    IN      ON      AT      SAVE    LETTER/S
Rule    AW      1974    only    -       Oct     lastSun 2:00s   1:00    -
Rule    AW      1975    only    -       Mar     Sun>=1  2:00s   0       -
Rule    AW      1983    only    -       Oct     lastSun 2:00s   1:00    -
Rule    AW      1984    only    -       Mar     Sun>=1  2:00s   0       -
Rule    AW      1991    only    -       Nov     17      2:00s   1:00    -
Rule    AW      1992    only    -       Mar     Sun>=1  2:00s   0       -
Rule    AW      2006    only    -       Dec      3      2:00s   1:00    -
Rule    AW      2007    2009    -       Mar     lastSun 2:00s   0       -
Rule    AW      2007    2008    -       Oct     lastSun 2:00s   1:00    -
Zone Australia/Perth     7:43:24 -      LMT     1895 Dec
                          8:00   Aus     WST     1943 Jul
                          8:00   AW      WST

I understand that Microsoft has a patch out, otherwise for Windows Xp
use this registry setting:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time
Zones\Australian Western Std. Time]
"Display"="(GMT+08:00) Perth"
"Dlt"="Australian West Daylight Time"

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