Re: [LEAPSECS] Consensus rather than compromise

From: John.Cowan <jcowan_at_REUTERSHEALTH.COM>
Date: Thu, 1 Sep 2005 10:46:57 -0400

Mark Calabretta scripsit:

> But DST is not the same as TZ - all these states are still basically
> UTC+10 and are not likely to change (that would probably be a federal
> issue anyway), so rationality is restored in winter! The world's
> timezones are pretty stable now after a few minor adjustments earlier
> last century.

Well, you can call it "minor" if you want, but when two-thirds of the
world's zones have changed at least once, that makes it look to me
like the rule, not the exception.

Australia *has* been pretty stable: its eleven zones (Adelaide, Brisbane,
Broken Hill, Currie, Darwin, Hobart, Lindeman, Lord Howe, Melbourne, and
Perth) have all remained fixed in offset since the beginning of LCT in
1895, except for the 1896 shift of Broken Hill from UTC+10h to UTC+9h,
the 1971 shift of Adelaide, Broken Hill, and Darwin from UTC+9h to
UTC+9h30m, and the 1981 shift of Lord Howe from UTC+10h to UTC+10h30m.
(N.B. The 1896 shift is *not* the reason Broken Hill is separated
from Sydney, since that event took place before the Epoch. Rather,
it is because Broken Hill adopted Adelaide's DST rules in 2001.)

I have done some work on the zoneinfo source data to generate a three-
column table summarizing the changes in the world's 365 time zones.
The table can be downloaded from .

The first column is the zone name in the form "continent/city" (city names
are more stable than country or state/province names). The second column
is the LCT offset. The third column is a name showing which of the 124
different sets of DST rules was in effect, or numeric value showing that
DST was (during some period) always in effect, or a hyphen if DST was
not in effect. The order of the rows does *not* reflect the historical
order of changes. The columns are tab-separated.

I have also posted the raw data, filled with helpful comments,
at . I have not included the
Antarctica information.

> Quirky exceptions like Kiribati, as noted by John Cowan,
> are so uncommon that they generate interest and don't really affect the
> argument.

Kiribati is exceptional because of the magnitude of the change. But
massaging the above data shows that Asia/Singapore, Asia/Kuala_Lumpur,
and Asia/Jakarta have changed their offsets six times each, and that
Europe/Vilnius, Europe/Simferopol, Europe/Chisinau, and Asia/Pontianak
have changed theirs five times each, some quite recently.

Just as a matter of interest, I also discovered that as of right now
there are 37 different time offsets in use: the integral hour offsets
from -11h to +14h, plus the following: -9h30m (Pacific/Marquesas),
-3h30m (America/St_Johns), +3h30m (Asia/Tehran), +4h30m (Asia/Kabul),
+5h30m (Asia/Calcutta), +5h45m (Asia/Katmandu), +6h30m (Asia/Rangoon),
+9h30m (the Yellow-Dog Dingo zones), +10h30m (Australia/Lord_Howe),
+11h30m (Pacific/Norfolk), and +12h45m (Pacific/Chatham).

> The proposal to introduce leap hours, with no means of coordinating
> them, means that the time zones themselves, will change secularly but
> in a disorganized manner.

Of course there are means of coordinating them. The EU is one such means,
and the federal U.S. and Australian governments are another. But in the
end LCT is an attribute of sovereignty, and individual governments will give
up just as much control as suits them.

John Cowan
Economists were put on this planet to make astrologers look good.
        --Leo McGarry
Received on Thu Sep 01 2005 - 07:47:58 PDT

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