Time zone codes
antoine.leca at renault.fr
Thu Jun 20 09:31:05 UTC 1996
Gwillim Law 919-852-4294 wrote a very interesting (to me) post:
> [snipped; see the original post]
> Note 3:
> A four-letter time zone code could be formed as follows:
> Letters 1-2 = ISO 3166 country code
> Letter 3 = position of time zone within country (A=westernmost or only,
> followed by B, C, D, ... moving eastward)
For a ethic point of view, I prefer going on the other way, because it follows the
sun. But it's only a point of view.
> Letter 4 = X for standard time, Y for DST (summer time), Z for standard
> time or DST depending on which is in force
> Using this scheme, and bearing in mind that the United States has six
> time zones (Hawaii-Aleutian, Alaska, Pacific, Mountain, Central, and
> Eastern), we would say that New York City is in the USFZ time zone. A
> particular local time in New York could be labeled, say, 9:13 USFX if it
> were in the winter; 4:30 pm USFY if it were in the summer; or 17:59 USFZ
> if it's not necessary to specify whether UTC-5 or UTC-4 is in force.
> (This is informal usage, of course. I'm not making any assumption about
> how time zone codes would interact with ISO 8601.) Since Arizona
> observes Mountain Standard Time year round, its time zone could be
> specified as USDX.
> This code has a few drawbacks. In some cases there would be many labels
> for what is logically the same time zone (in Europe, BEAZ, NLAZ, LUAZ,
> FRAZ, DEAZ, etc., would always mean the same thing, under existing
You can use the same policy as the one which is used for currency (ISO4217?): use a
code not for the country, but for the authority. And as EU is the authority (or a sort
of, I know the reality are laws voted by locales parlaments), and as XE is already
used for ECU, European Currency Unit (code XEC), we could name the EU timezones:
XEA? for WET/GMT etc. (more exactly: XEAX/XEAZ for GMT and XEAY for BST/IST
XEB? for MET/CET/MSZ/HEC... ;;-)
XEC? for EET
But then we can see immediatly a major drawback: What is the westernmost zone?
For EU, it is clearly WET/GMT, as the Azores are a "ultraperipherical province" (this
is an ugly translation of the French "région ultra-périphérique") like Guadeloupe or
the Reunion. From the ISO3166/ISO4217 point of view, Guadeloupe is in a different
part of the world, and incurred an different code (GP or XC for Caraibs/West Indies).
But as Azores are part of [the] Portugal, they have to be count under the XE
authority. So the Azores timezone (-0100/+0000 in summer) must be XEA?, and WET/GMT
must be XEB?, etc.
Even more difficult would be the case of the creation of a new timezone _not_ at the
eastern point (and we all know this is not a chimera).
In the first time, I was dreaming of a set of letters with fixed intervals; for not
having the "westernmost" problem, the set can be biased, that is allocated from the
middle af the alphabet (M). However, this don't work very good, because of the value
of the interval: obviously, 1 hour isn't sufficient, and in the today use we have to
use at least an 1/4 hour interval (for Chatham Is); and as far as Russia is on 13
timezones, we need at least 49 letters in the set. Pretty too much for the latin
alphabet (and the devanagari either, as he counts 48 letters ;-)
> likewise, Canada's CADZ would match USFZ). Conversely, there
> would be a few cases where two different time zones would have the same
> code. For example, in Australia, the states of Victoria and Tasmania
> are both on UTC+10 with a summer time that's UTC+11, but Tasmania begins
> summer time about a month before Victoria does. They would both be
> AUCZ. Also, for countries with remote territories like France (with its
> overseas departments Guadeloupe, Reunion, etc.), it would be doubtful
> whether the time zones for those territories should be included under
> the mother country: would FRAZ be used for France, or for Guadeloupe?
Good argument, but wrong example. According to ISO3166:1989, the mainland
("Metropolitan") France has the code FX, so the european timezone (mine) must be FXAZ;
and Guadeloupe/Martinique/Guyane (-0400 all year round) would be in GPAX/MQAX/GFAX,
Reunion (+0300) in REAX, and for French Polynesia, -1000 in PFAX, -0930 in PFBX and
-0900 in PFCX (etc.)
> If you reply that the set of time zones for a given country should match
> the territory included in the country's ISO 3166 code, I must point out
> that ISO 3166 tactfully refuses to specify the extent of each country on
> the map. ISO 3166 codes may not even represent disjoint territories.
> Gwillim Law | ENCOMPASS
> law at encmail.encompass.com | 1100 Crescent Green, Suite 210
> phone: 919-852-4294 | Cary, N.C. 27511-8106
> fax: 919-852-4299 | United States of America
And just for the fun: What about Antartica!!!
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