Dec. 6, 2011
2:08 p.m.
<yoshito_umaoka <at> us.ibm.com> writes: > > > What I have been able to find is a way to convert > from TZID (Olsen) > > to Windows > > timezone IDs using this URL: > > http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/zone_tzid.html > I'm planning to update the data to support multiple > TZID mapping (One Windows TZ -> Multiple TZIDs) in CLDR. I was considering > this before, but it's quite a tough task (also keeping data up-to-date > is not trivial). > It looks you're trying to create mapping data from > location to Windows time zone. You would find how difficult to achieve > this soon. > There are several type of issues. > 1) No matching UTC offset in Windows > For example, Australia/Eucla uses UTC+08:45 as base > offset, but there is no such zones in Windows time zone list. There are > several other instances. > 2) No matching daylight saving time rule in Windows > For example, Pacific/Easter observes daylight saving > time from August, 2011 to March 2012. However, Windows does not have any > UTC-06:00 zones supporting the daylight saving time rules (Windows UTC-06:00 > zones are all Northern Hemisphere type rules). > 3) Ambiguous mapping > For example, Windows has following time zones with > UTC+09:00 / no DST. > (UTC+09:00) Osaka, Sapporo, Tokyo > (UTC+09:00) Irkutsk > (UTC+09:00) Seoul > You have to decide one from above for some other territories > using UTC+09:00/no DST. For example, Asia/Dili, Asia/Jayapura, Pacific/Palau. > 4) Out of date data > You may want to map Belarus to (UTC+02:00) Minsk. > However, Minsk (Belarus) is currently using UTC+03:00/no DST. > Microsoft suggests Windows users in Belarus to use > (UTC+03:00) Kakiningrad for now [http://support.microsoft.com/kb/2625508]. > -Yoshito Hi, Thanks for the info. What you said makes me wonder even more Why Microsoft didn't go with TZID, and instead create their own half-baked substitute. A fine example of why standards are so important, and how the TZID system is of such great benefit to the world. In the end, I understand the flaws of Windows' time zone system, but I think I'll have to make do, as an alternative (for C#) would be many times the size of my own program. And I'm too keen on the user accessing the internet each time. Cheers, Dan