[tz] Request RE: academic research question re: TZ database
lyoncatch at shaw.ca
Thu Jan 9 14:15:07 UTC 2020
Thank-you both Paul and Scott for your insight.
I will modify my language in the future about calling the tz database a source of truth.
From: "Scott Kilpatrick" <skilpat at gmail.com>
To: "Paul Eggert" <eggert at cs.ucla.edu>
Cc: "lyoncatch" <lyoncatch at shaw.ca>, "tz" <tz at iana.org>
Sent: Thursday, January 9, 2020 7:08:41 AM
Subject: Re: [tz] Request RE: academic research question re: TZ database
Hope that helps you track down your software issue.
[ http://typesandtimes.net/ | https://typesandtimes.net ]
On Wed, Jan 8, 2020 at 8:07 PM Paul Eggert < [ mailto:eggert at cs.ucla.edu | eggert at cs.ucla.edu ] > wrote:
On 1/8/20 11:49 AM, Andrew Lyon wrote:
> It appears that many use the tz database as a source of truth.
Ouch. As we say in big letters, "The tz code and data are by no means
authoritative." < [ https://data.iana.org/time-zones/tz-link.html#changes | https://data.iana.org/time-zones/tz-link.html#changes ] >
> I understand there were 10 years between 1930 and 1941 when the hour of
> Spring daylight saving transition was 0000 (midnight) to 0100. I would
> like to confirm these entries are in the tz database.
Yes, tzdb says the 10 years 1930/1934 and 1937/1941 all did that, as can
be seen from the extract Brian emailed.
> I have numerous
> references that daylight saving time was also observed in
> America/Regina during world war ONE ( 1914-1918) and I am uncertain if
> those entries are in the tz database or the hour of those transitions.
As Brian mentioned, tzdb has these two transitions for 1918:
Sun Apr 14 08:59:59 1918 UT = Sun Apr 14 01:59:59 1918 MST
Sun Apr 14 09:00:00 1918 UT = Sun Apr 14 03:00:00 1918 MDT
Sun Oct 27 07:59:59 1918 UT = Sun Oct 27 01:59:59 1918 MDT
Sun Oct 27 08:00:00 1918 UT = Sun Oct 27 01:00:00 1918 MST
However, there's a good chance these data entries are incomplete for
Regina. It's also possible that the entries for 1930/1941 are wrong. For
details, please read the commentary for Regina in the northamerica file.
Here's the current development version:
[ https://github.com/eggert/tz/blob/master/northamerica | https://github.com/eggert/tz/blob/master/northamerica ]
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