Date: Mon, 31 Oct 2011 15:39:45 +0300 From: Konstantin Kivi <konst@sirena2000.ru> Message-ID: <4EAE9711.50408@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. kre