discrepancies between tz data and official Canadian time zone site
eggert at twinsun.com
Wed Aug 30 00:17:55 UTC 2000
I'm sending this email both to the Time Zone mailing list
<tz at elsie.nci.nih.gov> (see <http://www.twinsun.com/tz/tz-link.htm>
for more) and to the INMS feedback alias <questions.inms at nrc.ca>, as
it seems appropriate for both.
INMS, the Institute for National Measurement Standards in Ottawa
publishes the following information about standard and daylight saving
time zones in Canada:
http://www.nrc.ca/inms/time/tze.html (home page)
http://www.nrc.ca/inms/images/time/Tz99weB.jpg (standard time, 400 kB)
http://www.nrc.ca/inms/images/time/Tz99seB.jpg (daylight saving time, 400 kB)
The above web pages report the following information about times
since 1988 that disagree with the tz data:
* Newfoundland and New Brunswick switch at 00:01 local time, not 02:00.
* Manitoba switches from CDT to CST at 03:00 local time, not 02:00.
Since this reference seems authoritative, I'm inclined to believe
these claims and propose the corresponding changes to the tz data,
unless somebody suggests otherwise. This will require creating a new
tz Zone entry for New Brunswick; normally this would be
America/Saint_John but that's confusing given that there already is an
America/St_Johns, so perhaps America/Moncton is a better name.
Also, the INMS maps show both "legislated time zone boundaries" and
"observed time zones", with the following differences.
* British Columbia officially observes PST/PDT, but some parts of east
BC observe MST/MDT, and other parts observe MST all year (presumably
the America/Dawson_Creek zone of the tz data).
* A small area of east Saskatchewan observes CST/CDT, not CST.
* A small part of Ontario east of the -90 meridian observes CST/CDT
even though it's supposed to observe EST/EDT. Another small part
west of -90 observes EST/EDT even though it's supposed to observe
CST/CDT. And a third small part west of -90 observes EST all year.
* Officially, Quebec east of the -63 meridian is supposed to observe
AST all year. But nobody observes this. The western part of east
Quebec observes EST/EDT; the eastern part observes AST/ADT.
* Most of Labrador observes AST/ADT, even though it's officially
supposed to observe NST/NDT.
The observed time zones are all covered by existing tz entries, except
for the part of Ontario that observes EST all year. Does anybody know
more about where that is and how long they've observed EST?
The maps don't mention the Baffin time zone rebels reported at length
on the tz list. I'll mention the following URL for the benefit of the
More information about the tz