Subject: Time zones
Date: 14 Nov 1994 14:39:23 -0500
Organization: The Internet
I thank very much Mark Brader, from SoftQuad, for his very interesting
reference article from Richard B. Langley, on UT and UTC semantics, which
rights the inaccurate info I gave earlier. I was not able to get that
information so acurately before. So it will be part of my electronic references
from now on.
Now as promised, I post here the time zone abbreviations standardized in Canada
for both English and French in CAN/CSA-Z234.4-89 standard (I have added notes
and corrected minor typos still in the standard/ the abbreviations and numeric
and alphabetic time zones are correct in the standard, what I corrected would
not change any technical content).
Table A2 - Canadian Time Zones Abbreviations
(Abr<e'>viations des fuseaux horaires pour le Canada)
Standard Time Daylight Saving Time ITU Designator
Hours West French English French English
of UTC HN- -ST HA- -DT
2-1/2 - - HAT NDT -
3 - - HAA ADT P
3-1/2 HNT NST - - -
4 HNA AST HAE EDT Q
5 HNE EST HAC CDT R
6 HNC CST HAR MDT S
7 HNR MST HAP PDT T
8 HNP PST HAY YDT U
9 HNY YST - - V
HN stands for "Heure normale"/HA stands for "Heure avanc<e'>e"
ST stands for "Standard Time"/DT stands for "Dailight saving Time"
Prefix/Suffix meaning (note from ALB: I added the appropriate prepositions and
articles "du, de l', des, de" for non-French speakers,
so that the information of the standard be completed
for them - this data is not in any version of the std.):
A: Atlantic/de l'Atlantique
C: Central/du Centre
E: Eastern/de l'Est
M: Mountain (note from ALB: see R for French)
N: Newfoundland (note from ALB: see T for French)
P: Pacific/du Pacifique
R: des Rocheuses (note from ALB: see M for English)
T: de Terre-Neuve (note from ALB: see N for English)
Y: Yukon/du Yukon
Note: The standard says (I cite the English version textually): "Although there
is no ISO standard on time zone designators, the letters given in table A1 have
been adopted by the International Telecommunication Union (ITU/[UIT in
French]), a UN ["Nations Unies" in the French version, normally abbreviated
ONU] special agency having the status of treaty organization regarding radio
operations and regulations.
Within North America the abbreviations given in table A2 are also used."
The standard also deals with all-numeric dates and times (Repr<e'>sentation
num<e'>rique de la date et de l'heure). I invite those who want
non-time-zone-related information on this subject to buy the standard from CSA
(Canadian Standards Association/Association canadienne de normalisation) sales
offices throughout the world.
I only cited here the full table A2. Table A1 starts with Z for UTC, goes from
A to M East of UTC (with M as a half-zone) and N to Y West of UTC (with Y as a
half-zone); the Newfoundland half-zone does not seem covered by ITU/UIT,
despite it is on the soil where the first transatlantic (first long range) radio
transmissions were done by Marconi. Quarter zones are not covered either by
ITU, even if this does not affect Canada, but certain countries.
I also think that what would be good to document would be the dates on which
standard and daylight-saving time changes are done throughout the world. I have
not found that data in any place. I think it can *not* be done only on ITU
designators, as it has to take into account at least Northern/Sourthern
hemisphere and even national/multinational conventions and laws (for example,
this fall, Britain, Europe and North America have all switched to Standard Time
at different dates [3 dates...], sometimes at weeks of interval !!!) For other
countries it is quite problematic... from time to time, laws change too.
Perhaps there is a need for a worldwide registration authority for that
Gouvernement du Qu<e'>bec
Secr<e'>tariat du Conseil du tr<e'>sor
Service de la prospective et de la francisation
Subject: Re: Time zones
Date: 18 Nov 94 08:52:38 EST
In article <3a8edb$...@senator-bedfellow.MIT.EDU>, A...@immedia.ca (Alain
> I also think that what would be good to document would be the dates on which
> standard and daylight-saving time changes are done throughout the world. I
> have not found that data in any place. I think it can *not* be done only on
> ITU designators, as it has to take into account at least Northern/Sourthern
> hemisphere and even national/multinational conventions and laws ...
> Perhaps there is a need for a worldwide registration authority for that
The comp.std.internat newsgroup is a good place to find time zone-related
information. Its FAQ is available at the ftp server rtfm.mit.edu, under
/pub/usenet/news.answers/standards-faq. Quoting from that FAQ:
"Information about the world time standard UTC (e.g. when will the
next leap second be inserted in time, etc.) is available from the
'International Earth Rotation Service' (IERS) with anonymous
ftp from mesiom.obspm.circe.fr. There is no single official
document that defines the time zones, but a good collection of
information about time zones from Arthur David Olson is available
with ftp from elsie.nci.nih.gov in pub/tz*. It's updated periodically."
I've downloaded Olson's information. It includes historical data on the
changes between standard time and DST. It's very thorough, often going
back to the beginning of standard time. As a rule, each area within
which time standards have always been uniform is represented by one city
in that area (e.g. Saint John's for Newfoundland Time). There is only
anecdotal information about the geographical extent of each such area.
The best source I've found for current information about the changes
between standard time and DST is the Standard Schedules Information
Manual (SSIM), published by the International Air Transport Association
(IATA) every February and September. In Appendix F, it lists every
country served (i.e. every country from ISO standard 3166 that has one
or more airports), with its decomposition into time zones (if any) and
two years' worth of DST start and stop dates. These data come from
local informants (the airlines serving each location). To deduce the
geographical extent of each time zone, you would also want to consult
the location identifiers file, available on tape from IATA. For each of
about 10000 worldwide airports, you can deduce what time zone the
airport is in.
-- Gwillim Law
From: egg...@twinsun.com (Paul Eggert)
Subject: Re: Time zones
Date: 18 Nov 1994 10:49:57 -0800
Organization: Twin Sun Inc, El Segundo, CA, USA
References: <3a8edb$781@senator-bedfellow.MIT.EDU> <1994Nov18.085238.1@glvdev>
>I've downloaded Olson's information. It includes historical data on the
>changes between standard time and DST. It's very thorough, often going
>back to the beginning of standard time. As a rule, each area within
>which time standards have always been uniform is represented by one city
>in that area (e.g. Saint John's for Newfoundland Time).
Alas, the ``uniformity'' test in Olson's tables go back only to 1970,
the dawn of Unix time; for times before that, the Olson tables omit subregions.
For example, France had multiple time zones during World War II, and
the time zone that you were in depended on which army had passed
through your city most recently, but that information is not in the
Olson tables because it would be impractical to have a separate entry
for each French town (not to mention each Russian town, etc.).
The best source of historical time zone data that I know of is Thomas
Shanks, _The International Atlas_, Revised 3rd Editition (1991), and
_The American Atlas_, Expanded Fifth Edition (1993?), ACS Publications,
San Diego (telephone +1 619 297 9203). For example, Shanks has 20
8.5x11" pages of very small print on France, listing hundreds of French
cities, towns, and villages, with complete time zone history back to
the dawn of standard time for each (plus latitude and longitude, so
you can draw a map if you like).
Shanks is not infallible, and (unlike Olson or the airline tables) he
doesn't cover the many changes that have occurred since 1991, but if
you're interested in time zone history it's the best that I've found.