July 2010 - tz - lists.iana.org

Europe/Finland DST correction for years 1981 and 1982
by Janne Snabb July 14, 2010

July 14, 2010

Hi, I noticed that the Finland data is not accurate for years 1981 and 1982. During these two first trial years the DST adjustment was made one hour earlier than in forthcoming years. Starting 1983 the adjustment was made according to the central European standards. This is documented in Heikki Oja: Aikakirja 2007, published by The Almanac Office of University of Helsinki, ISBN 952-10-3221-9, available online (in Finnish) at: http://almanakka.helsinki.fi/aikakirja/Aikakirja2007kokonaan.pdf Page 105 (56 in PDF version) has a handy table of all past daylight savings transitions. It is easy enough to interpret without Finnish skills. This is also confirmed by Finnish Broadcasting Company's archive at: http://www.yle.fi/elavaarkisto/?s=s&g=1&ag=5&t=&a=3401 The news clip from 1981 says that "the time between 2 and 3 o'clock does not exist tonight". Thus Paul Eggert's comment in the file (above the relevant entry) is indeed correct. Please see the diff at the bottom of this message. I believe that it produces the desired results. I am not a member of this list, so please CC me with any further correspondence. Best Regards, -- Janne Snabb / EPIPE Communications snabb(a)epipe.com - http://epipe.com/ --- europe.orig 2009-09-09 15:19:43.000000000 +0300 +++ europe 2010-07-15 07:29:53.000000000 +0300 @@ -1023,14 +1023,16 @@ # since 1981. Go with Strang instead. # # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S Rule Finland 1942 only - Apr 3 0:00 1:00 S Rule Finland 1942 only - Oct 3 0:00 0 - +Rule Finland 1981 1982 - Mar lastSun 2:00 1:00 S +Rule Finland 1981 1982 - Sep lastSun 3:00 0 - # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Europe/Helsinki 1:39:52 - LMT 1878 May 31 1:39:52 - HMT 1921 May # Helsinki Mean Time - 2:00 Finland EE%sT 1981 Mar 29 2:00 + 2:00 Finland EE%sT 1983 2:00 EU EE%sT # Aaland Is Link Europe/Helsinki Europe/Mariehamn

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New time zone home (revisited)
by Olson, Arthur David (NIH/NCI) [E] July 14, 2010

July 14, 2010

It seems to have been overly ambitious to find both a new host and a new maintainter for the time zone stuff at the same time. So, one thing at a time. Who has insights on a workable options for new host(s) for the mailing list and the software distribution? --ado

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Double change on Apr 4th in America/Bahia_Banderas?
by Stuart Bishop July 14, 2010

July 14, 2010

Just looking into a failure in my test suite triggered by two timezone jumps within an hour: $ zdump -v America/Bahia_Banderas 2010 | grep 2010 America/Bahia_Banderas Sun Apr 4 06:59:59 2010 UTC = Sat Apr 3 23:59:59 2010 MST isdst=0 gmtoff=-25200 America/Bahia_Banderas Sun Apr 4 07:00:00 2010 UTC = Sun Apr 4 01:00:00 2010 CST isdst=0 gmtoff=-21600 America/Bahia_Banderas Sun Apr 4 07:59:59 2010 UTC = Sun Apr 4 01:59:59 2010 CST isdst=0 gmtoff=-21600 America/Bahia_Banderas Sun Apr 4 08:00:00 2010 UTC = Sun Apr 4 03:00:00 2010 CDT isdst=1 gmtoff=-18000 America/Bahia_Banderas Sun Oct 31 06:59:59 2010 UTC = Sun Oct 31 01:59:59 2010 CDT isdst=1 gmtoff=-18000 America/Bahia_Banderas Sun Oct 31 07:00:00 2010 UTC = Sun Oct 31 01:00:00 2010 CST isdst=0 gmtoff=-21600 Is this really correct, or should the timezone have jumped straight to CDT (-18000) at 0700 UTC? -- Stuart Bishop <stuart(a)stuartbishop.net> http://www.stuartbishop.net/

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Time zone confusion and implementation hints
by Yves Goergen July 10, 2010

July 10, 2010

Hi, I'm currently implementing an API for the tz database that should look like .NET's TimeZoneInfo class to replace that in my application. The API includes: * Convert a date and time from UTC to a time zone * Convert a date and time from a time zone to UTC * Return the base UTC offset of a time zone for a date and time * Return the save offset of a time zone for a date and time * Determine whether a date and time is ambiguous in a time zone * Determine whether a date and time is invalid in a time zone It will come with a code generator that "compiles" the text files into C# code so that there's no need to deploy additional files with the application. The API's internal data structures are very similar to the tz database records, these are already coded. Currently I'm stuck because of the flexibility of the tz rules. These can define transition times either in local, standard or universal time. Additionally, the caller of my API passes a date and time that is either local or universal. All this needs to be matched correctly. The right rule needs to be selected and there can be ambiguous or invalid times all along the way. It's not only hard to implement, it's also hard to describe, it's very confusing not to have a common base [zone] you can hold on to. I have now read about any manpage and code file from the tzcode distribution, starting with zic.c and going backwards in the list. I think the file localtime.c does the actual conversion but it's hard to read because it contains only few comments and uses short all-lowercase global variable names. I couldn't follow it to its core where the magic happens. I have analysed .NET's TimeZoneInfo implementation with .NET Reflector but it's not half as mighty as what the tz database can express. I also looked at the C# library ZoneInfo, but it uses an incompatible license, reads the text files at runtime and last but not least is quite inexact around transition times which it inacceptable for a calendar application. Also I think it's a good idea to write my own API for it because I'll need a Java port later as well, working on the exact same data. Could somebody assist me in this, please? Are there helpful thoughts to use when implementing such a programme? Right now my biggest problem is the transition times and in consequence finding the right rule to use for a given date and time. -- Yves Goergen "LonelyPixel" <nospam.list(a)unclassified.de> Visit my web laboratory at http://beta.unclassified.de

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Data request
by Rahim Bhimani July 9, 2010

July 9, 2010

Hello, Your website is useful. Thanks for managing the same. We tried to access your FTP site but were not able to get access of the same. Can you please send me the data through mail or let me know how else can we access the data. Would it be possible to get the data in following format : Country | City | timezone code | DST Start time | DST End time Will appreciate your prompt response. Warm Regards Rahim

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Olson programming language specific data sets
by Rich Tibbett July 4, 2010

July 4, 2010

Hi, I would like to request that the following resource be added to http://www.twinsun.com/tz/tz-link.htm: http://code.google.com/p/tzdata/ This project provides programming language specific representations of Olson timezone data. Currently this includes XML, PHP, Ruby, Javascript, JSON and CSV formatted data. The repository is updated as soon as the Olson FTP distribution is updated. All data can be downloaded as a zip and/or it can be obtained/synced via anonymous SVN. Data is made available under the MIT license. Thanks for all your hard work and I hope this resource will be of interest for people looking for language-specific timezone bindings. best regards, Rich Tibbett

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Problems with this mailing list?
by Yves Goergen July 4, 2010

July 4, 2010

Hi, I observe some strange behaviour with this mailing list. When trying to subscribe, nothing at all happened and after a second try, somebody seemed to have done that manually. This is a very irritating start for new people. I had sent a message to the list a few days ago which just didn't appear while a later one was sent around quite quickly. After a few hours I just resent my message and then it worked. I didn't receive any error message since then. It just got lost on the way with no notice. My mail server keeps informing me now that the delivery of my messages to the list is delayed by 24..48.. hours, but I already received the list's echo of the regarding message. I'm wondering what final error message my mail server will come up with when the retry timeout is over. The list's address is changed in all messages I get from it. Instead of tz(a)elsie.nci.nih.gov, my messages appear to be sent to tz(a)lecserver.nci.nih.gov. I even see messages to "tz(a)elsie.nci.nih.gov" <tz(a)lecserver.nci.nih.gov>... What is the real address now?! All very confusing here. I didn't observe such behaviour in any of the other 13 mailing lists I'm subscribed to... -- Yves Goergen "LonelyPixel" <nospam.list(a)unclassified.de> Visit my web laboratory at http://beta.unclassified.de

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Some questions about the database format
by Yves Goergen July 1, 2010

July 1, 2010

Hi, I intend to use the tz database in my C# calendar application. Since I need a decent time zone support, I was pointed to this database from the MSDN forums. I now have a few questions regarding the file format of the text files. A day specification of "Sun>=1" or "Sun>=8" should be clear, I interpret this as the first/second Sunday in a month. But what weekday and week is "Sun>=25" or "Sun>=2"? How is the Zone field "[UNTIL]" to be understood exactly? Is it including or excluding the given time? What does "1990" mean, is it until and inclusive the whole year 1990, ie /1990-12-31T23:59:59 or is it something around 1990-01-01? What does the time specification "2:00s" mean? I've seen it several times but couldn't make any sense of it. Are all rules in the text files sorted ascending by time ("FROM" year)? That would simplify the processing because in order to convert them into .NET framework structures I need pairs of DST start and end rules together for a range of years, and thus need to resolve the overlapping rule definitions.

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