[tz] Rule Russia incorrect
kre at munnari.OZ.AU
Mon Oct 31 14:51:29 UTC 2011
Date: Mon, 31 Oct 2011 15:39:45 +0300
From: Konstantin Kivi <konst at sirena2000.ru>
Message-ID: <4EAE9711.50408 at sirena2000.ru>
| Time Zone Data v. 2011m (Released 24 October 2011)
| file contains a line
| which I believe means that last change to summer time was in 2010.
Yes, that is the way we have it encoded.
| This is incorrect, because this (2011) year we actually have changed
| time on last Sunday of March (by moving clock forward)
The question is whether that change was to summer time, or a change
of timezone, altering standard time. The latter is the way the timezone
data has encoded it.
Note the entry in the Europe/Moscow zone data ...
3:00 Russia MSK/MSD 2011 Mar 27 2:00s
which says that as from Mar 27, 2011, the timezone is UTC+3 (whereas
it had been UTC+2 earlier).
This results in the transitions being ...
Europe/Moscow Sat Mar 27 22:59:59 2010 UTC = Sun Mar 28 01:59:59 2010 MSK isdst=0
Europe/Moscow Sat Mar 27 23:00:00 2010 UTC = Sun Mar 28 03:00:00 2010 MSD isdst=1
Europe/Moscow Sat Oct 30 22:59:59 2010 UTC = Sun Oct 31 02:59:59 2010 MSD isdst=1
Europe/Moscow Sat Oct 30 23:00:00 2010 UTC = Sun Oct 31 02:00:00 2010 MSK isdst=0
Europe/Moscow Sat Mar 26 22:59:59 2011 UTC = Sun Mar 27 01:59:59 2011 MSK isdst=0
Europe/Moscow Sat Mar 26 23:00:00 2011 UTC = Sun Mar 27 03:00:00 2011 MSK isdst=0
Note that in 2010, when the time (in March) moved from UTC+2 to UTC+3,
isdst becomes 1. On the other hand, when the similar change occurred
in March 2011, from UTC+2 to UTC+3, isdst remains at 0.
Now it is certainly true that this could be coded either way, and if
the common opinion in Russia is that you now have summer time (or
daylight saving) turned on all year around, then perhaps we should
switch the way it is done. On the other hand, if the view is that
you now have a different standard time than before, and no more summer
time (daylight saving), then the way it is now seems better.
Either way, the timestamps are (I think) correct, the only difference is
whether we consider summer time is turned on or not.
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