"32 time zones"

Paul Eggert eggert at twinsun.com
Tue Jun 8 19:38:53 UTC 1993

I don't know where tog's magic number of 32 time zones came from, but it's
clearly too small.  My best guess at the true current number is 35.  Here's
how I derived it.  There are 25 time zones that are an integral number of
hours offset from GMT, ranging from GMT -1200 (Kwajalein) to GMT +1200 (New
Zealand).  All are in use somewhere (but see comments on Kwajalein below).
Here are the 12 other zones described in Olson's usno1989 file; see SunOS
4.x's /usr/share/lib/zoneinfo/usno1989 (why did they remove this info from
SunOS 5?):

	-0930 Marquesas Is; Cook Is; French Polynesia
	-0330 Newfoundland; -0130 Newfoundland Daylight
	+0330 Iran
	+0430 Afghanistan
	+0530 India; Sri Lanka
	+0545 Nepal
	+0630 Myanmar (Burma); Cocos I
	+0930 South Australia; +1030 South Australia Summer
	+1130 Norfolk I
	+1245 Chatham Is

That's 10 non-integral zones, so the total number is 25 + 10 = 35.  I'm not
counting the Arabian peninsula, which (rumor has it) uses solar time, not time
zones.  Nor am I counting daylight savings time as a separate zone.  And
no doubt there are some errors in usno1989, so this number is not definitive.

abe listed a bunch of time zones like ``Java Time'' that are no longer in use,
at least according to usno1989.  I think those zones date back to colonial
times.  Also, usno1989's info for the ex-Soviet Union is woefully out of date
due to the March 1991 time zone reforms in the (then-) SU.  E.g. I think
Uelen is now +1200 (+1300 summer), not +1300 (+1400 summer).

Kwajalein is a special case -- it's west of the International Date Line but
usno1989 says it's 12 hours behind GMT!  Perhaps it's a typo in usno1989, and
should be +1200?  Or perhaps they prefer being closer to US/Pacific time since
they're the target of ICBMs from Vandenberg.

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