TZ database content

John A. Halloran seagoat at
Sun Feb 11 17:30:39 UTC 2001

At 04:12 PM 02/11/01 +0700, Robert Elz <kre at munnari.OZ.AU> wrote:

>There's no hope (other than by forcing unrelated named) to make timezone
>name abbreviations unique.   Most of us simply recognised that as an
>impossibility a long time ago.   You can impose your own set of abbreviations
>on whatever you control, but you're not going to convince many others to
>go along with your set.
>A large part of the world don't have names for timezones, let alone
>abbreviations for them - there is simply "the time", which you can
>pretend is called "The time in XXX" or "XXX time" for some country
>name XXX (or region), but that's just you inventing that label.
>Numeric zone offsets are easier to manipulate, make just as much
>sense, and are much less ambiguous.   We should just stick to using

There are good reasons for developing standardized time zone abbreviations.
 The abbreviation acts as a key to retrieve a full time zone name that is
meaningful to the local user.  The abbreviation tells whether the hour in
question is standard time or daylight/summer time.  With just a numeric
hour, you lose that information.  If you do go the numeric route, then it
should consist of two parts: the standard time zone hour:minutes and the
current offset from the standard time zone, whether 0 or -1 or whatever the
politicians have in effect.  However, you lose the ability to pull up a
local name.  I see no problem with having more than one abbreviation for a
particular zone hour, if that allows retrieval of Israel Standard Time
versus Eastern European Time, for example.

But, there is competition for certain common abbreviations, such as both
Israel and India competing for IST.  This is where an organization such as
the ISO, with which I have no connections, would need to make the hard
choices.  There is a parallel with the procedure for arriving at ISO
country codes and language codes.  To show you what I mean, here is a
proposal for ISO language codes that appeared on the Linguist List on Feb.
4, 2000.

>1. ISO 639: language codes
>ISO 639 is one of many international standards developed by groups of
>experts in many countries. This section provides a simplified view.
>Put simply, ISO 639's job is to provide simple codes that can be
>embedded in (mainly computerised) information systems that can allow
>these information systems to highlight language use, or even to
>enable useful things like font switching or similar, e.g. on Internet
>web sites.
>There are older 2-letter codes used, it could be said, mainly in
>older, "legacy" system. 3-letter codes (mainly identical with codes
>used by the Library of Congress, and in many libraries) have seen the
>largest growth, and allow for greater expansion. Actually the two
>sets are currently listed in two separate parts of ISO 639,
>respectively in ISO [WD] 639[-1] and ISO 639-2.
>The Internet Engineering Task Force's specification RFC 1766
>recommends the use of ISO 639 codes in Internet uses.
>We have also been in discussion with the Summer Institute of
>Linguistics (SIL) who use a different (and much larger) set of
>3-letter codes in their Ethnologue, codes which have also been used
>in some Internet situations.
>- ----------------------------------------------------------
>  LC  ISO 639-2   ISO 639-1  Language name in English
>- ----------------------------------------------------------
>  --- --- ---     (aj)       Abaza
>      abk          ab        Abkhazian
>  --- --- ---     (ad)       Adyge
>      ace                    Achinese
>      ach                    Acoli
>      ada                    Adangme
>      aar          aa        Afar
>      afh                    Afrihili
>      afr          af        Afrikaans
>      afa                    Afro-Asiatic (Other)
>      aka          ak        Akan
>      akk                    Akkadian
>      alb/sqi *    sq        Albanian
>      ale                    Aleut
>      alg                    Algonquian languages
>  --- --- ---     (an)       Aragonese
>      tut                    Altaic (Other)
>      amh          am        Amharic
>      apa                    Apache languages
>      ara          ar        Arabic
>      arc                    Aramaic
>      arp                    Arapaho

You can see that there is competition for certain abbreviations, and that
the choice of who gets what can be arbitrary.  But as the creators say,
they have tried to follow existing conventions as much as possible.

The Unix time zone volunteers have as much right as any to decide on the
conventions for computer/Internet time zone reference.  Since the list
subscribers are representative of the current world spread of computer
usage, it would be fair to have nominations for unique abbreviations (from
2 to 5 letters) and tally the votes for and against.


John Halloran, Halloran Software
P.O. Box 75713, Los Angeles, CA 90075 U.S.A.
e-mail: seagoat at

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