> I'm pretty sure timelocal() is wrong here, though I'm not sure why. There > was no DST transition in that zone in 1910. In fact, there wasn't really a > time zone until 1918. The pre-1918 zone file in the Olson database is just > using local solar time, but it's not very meaningful. If you really care > about local times in the early 1900s you probably need to calculate the > solar noon for the given lat/long.
This is likely to be a Y2K/19100 window wrap issue. The little dst.pl script that I use to check Olson DB -- used in 2007 to diagnose which servers needed Olson/TZ DB update -- also reports DST transitions for 2010 when asked for 1910. [ i think i grabbed it from blogs.perl.org and enhanced it ? no authorship is noted ] $ dst.pl -y 1910 Sun Mar 14 01:59:59 EST 2010 --> Sun Mar 14 03:00:00 EDT 2010 Sun Nov 07 01:59:59 EDT 2010 --> Sun Nov 07 01:00:00 EST 2010 (That script uses localtime(), Time::Local and POSIX qw(strftime), but not DateTime.) Supporting evidence -- Early November DST transition was novel in 2007. (Giving the little trick-or-treaters the extra hour of daylight at Hallowe'en was obviously desirable for decades, but it took until 2007 to get it done.) I predict Lu's script will report DST transitions morning of Apr 2 and Oct 29 in 1906, since those were the dates in 2006. -- Bill Ricker bill.n1...@gmail.com https://www.linkedin.com/in/n1vux
