- tz - lists.iana.org

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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When will 2010k be released ?
by Rajput, Sonali June 30, 2010

June 30, 2010

Hi, Any plans for the k release ? Thanks Sonali

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FW: .NET implementation for tz compiler list
by Olson, Arthur David (NIH/NCI) [E] June 21, 2010

June 21, 2010

I'm forwarding this message from Colin Bowern who is not on the time zone mailing list. Those of you who are on the list, please direct replies appropriately. --ado From: Colin Bowern [mailto:colin@bowern.com] Sent: Wednesday, June 16, 2010 2:28 To: tz(a)lecserver.nci.nih.gov Subject: .NET implementation for tz compiler list Just wanted to give everyone a heads up that there is a Joda Time port for .NET in progress: http://code.google.com/p/noda-time/ It's starting to gather some steam. Cheers, Colin

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.NET implementation for tz compiler list
by Colin Bowern June 16, 2010

June 16, 2010

Just wanted to give everyone a heads up that there is a Joda Time port for .NET in progress: http://code.google.com/p/noda-time/ It's starting to gather some steam. Cheers, Colin

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FW: Patches for zic.8 manpage
by Olson, Arthur David (NIH/NCI) [E] June 14, 2010

June 14, 2010

I'm forwarding this message from Uli, who is not on the time zone mailing list. Those of you who are on the list, please direct replies appropriately. The zic.8 file that's part of the original distribution at ftp://elsie.nci.nih.gov/pub doesn't contain ".Dl" lines. My best guess is that these are being introduced by a redistributor; someone on the list may have insights. --ado Hello, not sure if this is the right list to submit "code" changes to, but as I'm working on getting the FreeBSD manpage corpus into shape for mandoc/mdocml, there's a patch I'd like you to commit. The patch fixes some missing quotes. Regards, Uli diff --git a/contrib/tzcode/zic/zic.8 b/contrib/tzcode/zic/zic.8 index f7ff815..fe09ef2 100644 --- a/contrib/tzcode/zic/zic.8 +++ b/contrib/tzcode/zic/zic.8 @@ -120,9 +120,9 @@ Non-blank lines are expected to be of one of three types: rule lines, zone lines, and link lines. .Pp A rule line has the form: -.Dl "Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S +.Dl "Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S" For example: -.Dl "Rule US 1967 1973 \- Apr lastSun 2:00 1:00 D +.Dl "Rule US 1967 1973 \- Apr lastSun 2:00 1:00 D" .Pp The fields that make up a rule line are: .Bl -tag -width "LETTER/S" -offset indent @@ -262,7 +262,7 @@ the variable part is null. A zone line has the form: .Dl "Zone NAME GMTOFF RULES/SAVE FORMAT [UNTILYEAR [MONTH [DAY [TIME]]]]" For example: -.Dl "Zone Australia/Adelaide 9:30 Aus CST 1971 Oct 31 2:00 +.Dl "Zone Australia/Adelaide 9:30 Aus CST 1971 Oct 31 2:00" The fields that make up a zone line are: .Bl -tag -width indent .It NAME @@ -319,9 +319,9 @@ continuation. .El .Pp A link line has the form -.Dl "Link LINK-FROM LINK-TO +.Dl "Link LINK-FROM LINK-TO" For example: -.Dl "Link Europe/Istanbul Asia/Istanbul +.Dl "Link Europe/Istanbul Asia/Istanbul" The .Em LINK-FROM field should appear as the @@ -335,9 +335,9 @@ Except for continuation lines, lines may appear in any order in the input. .Pp Lines in the file that describes leap seconds have the following form: -.Dl "Leap YEAR MONTH DAY HH:MM:SS CORR R/S +.Dl "Leap YEAR MONTH DAY HH:MM:SS CORR R/S" For example: -.Dl "Leap 1974 Dec 31 23:59:60 + S +.Dl "Leap 1974 Dec 31 23:59:60 + S" The .Em YEAR , .Em MONTH ,

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proposed time zone package changes (Bahia de Banderas; version naming)
by Arthur David Olson June 14, 2010

June 14, 2010

Here are proposed changes to the time zone package: northamerica New "Bahia_Banderas" time zone (omitting the "de" to stay within 14 characters) zone.tab New "Bahia_Banderas" time zone tz-link.htm Add sentence on time zone version naming. If no problems are found, these should show up on the ftp site on 2010-05-10. --ado ------- northamerica ------- *** /tmp/geta2310 Sat May 1 10:13:44 2010 --- /tmp/getb2310 Sat May 1 10:13:44 2010 *************** *** 1,5 **** # <pre> ! # @(#)northamerica 8.30 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. --- 1,5 ---- # <pre> ! # @(#)northamerica 8.31 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. *************** *** 2089,2095 **** --- 2089,2132 ---- -8:00 - PST 1970 -7:00 Mexico M%sT 1999 -7:00 - MST + + # From Alexander Krivenyshev (2010-04-21): + # According to news, Bahía de Banderas (Mexican state of Nayarit) + # changed time zone UTC-7 to new time zone UTC-6 on April 4, 2010 (to + # share the same time zone as nearby city Puerto Vallarta, Jalisco). + # + # (Spanish) + # Bahía de Banderas homologa su horario al del centro del + # país, a partir de este domingo + # <a href="http://www.nayarit.gob.mx/notes.asp?id=20748"> + # http://www.nayarit.gob.mx/notes.asp?id=20748 + # </a> + # + # Bahía de Banderas homologa su horario con el del Centro del + # País + # <a href="http://www.bahiadebanderas.gob.mx/principal/index.php?option=com_content&vi…"> + # http://www.bahiadebanderas.gob.mx/principal/index.php?option=com_content&vi…" + # </a> + # + # (English) + # Puerto Vallarta and Bahía de Banderas: One Time Zone + # <a href="http://virtualvallarta.com/puertovallarta/puertovallarta/localnews/2009-12-…"> + # http://virtualvallarta.com/puertovallarta/puertovallarta/localnews/2009-12-… + # </a> + # + # or + # <a href="http://www.worldtimezone.com/dst_news/dst_news_mexico08.html"> + # http://www.worldtimezone.com/dst_news/dst_news_mexico08.html + # </a> + # + # "Mexico's Senate approved the amendments to the Mexican Schedule System that + # will allow Bahía de Banderas and Puerto Vallarta to share the same time + # zone ..." # Baja California Sur, Nayarit, Sinaloa + + # From Arthur David Olson (2010-05-01): + # Use "Bahia_Banderas" to keep the name to fourteen characters. + Zone America/Mazatlan -7:05:40 - LMT 1921 Dec 31 23:54:20 -7:00 - MST 1927 Jun 10 23:00 -6:00 - CST 1930 Nov 15 *************** *** 2100,2105 **** --- 2137,2155 ---- -7:00 - MST 1949 Jan 14 -8:00 - PST 1970 -7:00 Mexico M%sT + + Zone America/Bahia_Banderas -7:01:00 - LMT 1921 Dec 31 23:59:00 + -7:00 - MST 1927 Jun 10 23:00 + -6:00 - CST 1930 Nov 15 + -7:00 - MST 1931 May 1 23:00 + -6:00 - CST 1931 Oct + -7:00 - MST 1932 Apr 1 + -6:00 - CST 1942 Apr 24 + -7:00 - MST 1949 Jan 14 + -8:00 - PST 1970 + -7:00 Mexico M%sT 2010 Apr 4 + -6:00 Mexico C%sT + # Baja California (near US border) Zone America/Tijuana -7:48:04 - LMT 1922 Jan 1 0:11:56 -7:00 - MST 1924 ------- tz-link.htm ------- *** /tmp/geta2330 Sat May 1 10:14:05 2010 --- /tmp/getb2330 Sat May 1 10:14:05 2010 *************** *** 18,24 **** <body> <h1>Sources for Time Zone and Daylight Saving Time Data</h1> <address> ! @(#)tz-link.htm 8.26 </address> <p> This file is in the public domain, so clarified as of --- 18,24 ---- <body> <h1>Sources for Time Zone and Daylight Saving Time Data</h1> <address> ! @(#)tz-link.htm 8.27 </address> <p> This file is in the public domain, so clarified as of *************** *** 89,94 **** --- 89,96 ---- where <code><var>C</var></code> is the code's version; similarly, the data are in <code>tzdata<var>D</var>.tar.gz</code>, where <code><var>D</var></code> is the data's version. + Each version is a four-digit year followed by lower-case letters + (a through z, then za through zz, then zza through zzz, and so on). The following <a href="http://en.wikipedia.org/wiki/Unix_shell">shell</a> commands download these files to a <abbr>GNU</abbr>/Linux or similar host; ------- zone.tab ------- *** /tmp/geta2358 Sat May 1 10:14:46 2010 --- /tmp/getb2358 Sat May 1 10:14:46 2010 *************** *** 1,5 **** # <pre> ! # @(#)zone.tab 8.35 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. # --- 1,5 ---- # <pre> ! # @(#)zone.tab 8.36 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. # *************** *** 288,293 **** --- 288,294 ---- MX +2904-11058 America/Hermosillo Mountain Standard Time - Sonora MX +3232-11701 America/Tijuana US Pacific Time - Baja California near US border MX +3018-11452 America/Santa_Isabel Mexican Pacific Time - Baja California away from US border + MX +2048-10515 America/Bahia_Banderas Mexican Central Time - Bahia de Banderas MY +0310+10142 Asia/Kuala_Lumpur peninsular Malaysia MY +0133+11020 Asia/Kuching Sabah & Sarawak MZ -2558+03235 Africa/Maputo

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