I wonder why the dst transition hours are encoded in local time. Wouldn't it be easier to do it in UTC? There is no need to differentiate between the same hour before and after change then.
Suppose in local time (which is, say, UTC+3) the DST transition is on something like "last Sunday of 10th month at 02:00", which might then in UTC become "last Saturday of 10th month at 23:00, except if that Saturday is the last day of the month, then the second to last Saturday". In effect, if conversion to UTC causes the transition to move to a different day, it might also be on a different week or month, causing headache.
(Or did you ask something else entirely? It wouldn't be the first time I misunderstood things about time zones.)
I bet it's North America bias—we roll our time changes across the continent one TZ at a time, at 2am local time (which also explains why the default is "/2").
Perhaps to decouple DST transition rules from other time-zone changes. So if the time-zone offset is adjusted for some other reason then the DST rule does not also need to be changed.
taneliv|1 year ago
(Or did you ask something else entirely? It wouldn't be the first time I misunderstood things about time zones.)
blahedo|1 year ago
winternewt|1 year ago