Timezone offsets aren't applying DST

August 25, 2006 6:22 PM

Hey Matt, you're applying daylight saving time to timezones labeled as "UTC+-X (someplace)" in preferences...
posted by qvantamon to Bugs at 6:22 PM (9 comments total)

Specially, UTC-3 is labeled as Atlantic Time, but, right now, Atlantic Time is really UTC-2 (and that's what's being show on MeFi when you choose UTC-3 timezone).

Yeah, I know I can fix that by choosing another value from the list, but the wrong UTC offset on the label bugs me :(

Also, in another time-related stuff, both live preview and preview show up in PST.
posted by qvantamon at 6:27 PM on August 25, 2006

Yeah, I've read all the threads before about applying dst to everyone... the peeve isn't about it, it's just that the labels are wrong.

Changing the labels to "Server + 1, Server +2" (along with the corresponding labels like Atlantic Time) should be fine :)
posted by qvantamon at 6:33 PM on August 25, 2006

I agree. I understand why you can't make everyone's times match their actual times, but it's probably then just easier to drop the labels (which are wrong 6 months out of the year) and just make them "server +1" or the like.
posted by Bugbread at 6:54 PM on August 25, 2006

This is easy to fix with a database lookup table, and I described how to do so in detail the last time this came up.
posted by orthogonality at 7:14 PM on August 25, 2006

Timezones are a bitch. This is a hack. It works good enough for most people but isn't perfect. I don't lose sleep over it.
posted by mathowie (staff) at 8:54 PM on August 25, 2006

Orthogonality: Here in Brazil the time of the year DST comes into effect and goes away is decided by the government, every year. I bet this isn't the only case. This year Windows XP (which is maintained by a big, global company, with a big local office) had the incorrect time zone for a few days because the government decided to apply DST earlier. Linux too, before you bring that up, the update to the tz files hit APT/Portage after a few days of incorrect time. Timezones are a bitch. There sure are ways to get an approximately good functionality, but I respect Matt not willing to mess with that.

I don't mind switching my timezone twice a year. It's just that the current labels itch.
posted by qvantamon at 9:20 PM on August 25, 2006

Getting rid of DST - a MeFi project?
Let those who wish to stretch the daylight get up an hour earlier if they wish, but leave the rest of us in real time.
posted by Cranberry at 9:49 PM on August 25, 2006

Timezones are a bitch. This is a hack. It works good enough for most people but isn't perfect. I don't lose sleep over it.

Matt, I love you. This is exactly how I feel about timezones in webapp development. And the new rules taking effect next year make it even worse.
posted by Plutor at 1:46 PM on August 26, 2006

Incidentally, I have written C code that handles timezone adjustments (including the 2007 US rules), or allows input of arbitrary DST in a three formats, the third very similar to POSIX TZ format 2:

DSTBegins and DSTEnds may be given in the following three formats:,
1 as an integral number, the Julian day of the year DST starts or ends, e.g., 92,

2 as an integral number prefixed by the letter J, the Julian Day with Leap Days ignored;
(1 will be added to the number if the year is a Leap Year and day > 28),

3 (preferred) the letter "M" followed by the month [1-12], followed by a period,
week [1-5], 5 meaning the last week of the month, followed by a period,
day [0-6], 0 meaning Sunday, 6 meaning Saturday,
Any DST format can be followed by a slash and a real number,
giving the hour (in local time) that DST starts or ends,
e.g., "2" 2am, "5.5" 5:30am.

for years 2006 and prior,
if not given DSTStart defaults to "M4.1.0/2", 2am the first Sunday of April,
if not given DSTEnd defaults to "M10.5.0/2", 2am the last Sunday of October,
for years 2007 and after,
if not given DSTStart defaults to "M3.2.0/2", 2am the second Sunday of March,
if not given DSTEnd defaults to "M11.1.0/2", 2am the first Sunday of November.


The code is available on request.
posted by orthogonality at 5:24 PM on August 26, 2006