On 2014-07-06, at 23:07, Robert A. Rosenberg wrote: > At 09:10 -0700 on 06/28/2014, Hardee, Chuck wrote about Re: Local Time > conversion to/from UTC Time: > >> I'm looking for information on how local time to UTC, and vice versa, is >> affected by a locale's Daylight Savings Time state. > > Converting UTC to Local time for historical data is no problem so long as you > know the DST switch dates for the locale. Switching from local to UTC needs > the same info but is harder for the FALL switch date due to the repeat of the > 1AM-1:59AM Hour since there are two of them on switch date. If you have a > series of time stamps (or no time stamps for 1AM-1:59AM) then you just use a > 1:xx time stamp occurring after a much later 1:xx one to mark the switch from > ST to DST. For SPRING there will be no 2:xx so anything from 3AM on is ST.
I believe you have that backwards. In FALL, switch from DST to ST; in SPRING from ST to DST. -- gil
