September 2013 - tz - lists.iana.org

tzcode2013e and tzdata2013e available
by Paul Eggert Sept. 24, 2013

Sept. 24, 2013

The 2013e release of the tz code and data is available. It reflects the following changes circulated on the tz mailing list: Changes affecting near-future time stamps This year Fiji will start DST on October 27, not October 20. (Thanks to David Wheeler for the heads-up.) For now, guess that Fiji will continue to spring forward the Sunday before the fourth Monday in October. Changes affecting current and future time zone abbreviations Use WIB/WITA/WIT rather than WIT/CIT/EIT for alphabetic Indonesian time zone abbreviations since 1932. (Thanks to George Ziegler, Priyadi Iman Nurcahyo, Zakaria, Jason Grimes, Martin Pitt, and Benny Lin.) This affects Asia/Dili, Asia/Jakarta, Asia/Jayapura, Asia/Makassar, and Asia/Pontianak. Use ART (UTC-3, standard time), rather than WARST (also UTC-3, but daylight saving time) for San Luis, Argentina since 2009. Changes affecting Godthab time stamps after 2037 if version mismatch Allow POSIX-like TZ strings where the transition time's hour can range from -167 through 167, instead of the POSIX-required 0 through 24. E.g., TZ='FJT-12FJST,M10.3.1/146,M1.3.4/75' for the new Fiji rules. This is a more-compact way to represent far-future time stamps for America/Godthab, America/Santiago, Antarctica/Palmer, Asia/Gaza, Asia/Hebron, Asia/Jerusalem, Pacific/Easter, and Pacific/Fiji. Other zones are unaffected by this change. (Derived from a suggestion by Arthur David Olson.) Allow POSIX-like TZ strings where daylight saving time is in effect all year. E.g., TZ='WART4WARST,J1/0,J365/25' for Western Argentina Summer Time all year. This supports a more-compact way to represent the 2013d data for America/Argentina/San_Luis. Because of the change for San Luis noted above this change does not affect the current data. (Thanks to Andrew Main (Zefram) for suggestions that improved this change.) Where these two TZ changes take effect, there is a minor extension to the tz file format in that it allows new values for the embedded TZ-format string, and the tz file format version number has therefore been increased from 2 to 3 as a precaution. Version-2-based client code should continue to work as before for all time stamps before 2038. Existing version-2-based client code (tzcode, GNU/Linux, Solaris) has been tested on version-3-format files, and typically works in practice even for time stamps after 2037; the only known exception is America/Godthab. Changes affecting time stamps before 1970 Pacific/Johnston is now a link to Pacific/Honolulu. This corrects some errors before 1947. Some zones have been turned into links, when they differ from existing zones only in older data that was likely invented or that differs only in LMT or transition from LMT. These changes affect only time stamps before 1943. The affected zones are: Africa/Juba, America/Anguilla, America/Aruba, America/Dominica, America/Grenada, America/Guadeloupe, America/Marigot, America/Montserrat, America/St_Barthelemy, America/St_Kitts, America/St_Lucia, America/St_Thomas, America/St_Vincent, America/Tortola, and Europe/Vaduz. (Thanks to Alois Treindl for confirming that the old Europe/Vaduz zone was wrong and the new link is better for WWII-era times.) Change Kingston Mean Time from -5:07:12 to -5:07:11. This affects America/Cayman, America/Jamaica and America/Grand_Turk time stamps from 1890 to 1912. Change the UT offset of Bern Mean Time from 0:29:44 to 0:29:46. This affects Europe/Zurich time stamps from 1853 to 1894. (Thanks to Alois Treindl). Change the date of the circa-1850 Zurich transition from 1849-09-12 to 1853-07-16, overriding Shanks with data from Messerli about postal and telegraph time in Switzerland. Changes affecting time zone abbreviations before 1970 For Asia/Jakarta, use BMT (not JMT) for mean time from 1923 to 1932, as Jakarta was called Batavia back then. Changes affecting API The 'zic' command now outputs a dummy transition when far-future data can't be summarized using a TZ string, and uses a 402-year window rather than a 400-year window. For the current data, this affects only the Asia/Tehran file. It does not affect any of the time stamps that this file represents, so zdump outputs the same information as before. (Thanks to Andrew Main (Zefram).) The 'date' command has a new '-r' option, which lets you specify the integer time to display, a la FreeBSD. The 'tzselect' command has two new options '-c' and '-n', which lets you select a zone based on latitude and longitude. The 'zic' command's '-v' option now warns about constructs that require the new version-3 binary file format. (Thanks to Arthur David Olson for the suggestion.) Support for floating-point time_t has been removed. It was always dicey, and POSIX no longer requires it. (Thanks to Eric Blake for suggesting to the POSIX committee to remove it, and thanks to Alan Barrett, Clive D.W. Feather, Andy Heninger, Arthur David Olson, and Alois Treindl, for reporting bugs and elucidating some of the corners of the old floating-point implementation.) The signatures of 'offtime', 'timeoff', and 'gtime' have been changed back to the old practice of using 'long' to represent UT offsets. This had been inadvertently and mistakenly changed to 'int_fast32_t'. (Thanks to Christos Zoulos.) The code avoids undefined behavior on integer overflow in some more places, including gmtime, localtime, mktime and zdump. Changes affecting the zdump utility zdump now outputs "UT" when referring to Universal Time, not "UTC". "UTC" does not make sense for time stamps that predate the introduction of UTC, whereas "UT", a more-generic term, does. (Thanks to Steve Allen for clarifying UT vs UTC.) Data changes affecting behavior of tzselect and similar programs Country code BQ is now called the more-common name "Caribbean Netherlands" rather than the more-official "Bonaire, St Eustatius & Saba". Remove from zone.tab the names America/Montreal, America/Shiprock, and Antarctica/South_Pole, as they are equivalent to existing same-country-code zones for post-1970 time stamps. The data for these names are unchanged, so the names continue to work as before. Changes affecting code internals zic -c now runs way faster on 64-bit hosts when given large numbers. zic now uses vfprintf to avoid allocating and freeing some memory. tzselect now computes the list of continents from the data, rather than have it hard-coded. Minor changes pacify GCC 4.7.3 and GCC 4.8.1. Changes affecting the build procedure The 'leapseconds' file is now generated automatically from a new file 'leap-seconds.list', which is a copy of <ftp://time.nist.gov/pub/leap-seconds.list>. A new source file 'leapseconds.awk' implements this. The goal is simplification of the future maintenance of 'leapseconds'. When building the 'posix' or 'right' subdirectories, if the subdirectory would be a copy of the default subdirectory, it is now made a symbolic link if that is supported. This saves about 2 MB of file system space. The links America/Shiprock and Antarctica/South_Pole have been moved to the 'backward' file. This affects only nondefault builds that omit 'backward'. Changes affecting version-control only .gitignore now ignores 'date'. Changes affecting documentation and commentary Changes to the 'tzfile' man page It now mentions that the binary file format may be extended in future versions by appending data. It now refers to the 'zdump' and 'zic' man pages. Changes to the 'zic' man page It lists conditions that elicit a warning with '-v'. It says that the behavior is unspecified when duplicate names are given, or if the source of one link is the target of another. Its examples are updated to match the latest data. The definition of white space has been clarified slightly. (Thanks to Michael Deckers.) Changes to the 'Theory' file There is a new section about the accuracy of the tz database, describing the many ways that errors can creep in, and explaining why so many of the pre-1970 time stamps are wrong or misleading (thanks to Steve Allen, Lester Caine, and Garrett Wollman for discussions that contributed to this). The 'Theory' file describes LMT better (this follows a suggestion by Guy Harris). It refers to the 2013 edition of POSIX rather than the 2004 edition. It's mentioned that excluding 'backward' should not affect the other data, and it suggests at least one zone.tab name per inhabited country (thanks to Stephen Colebourne). Some longstanding restrictions on names are documented, e.g., 'America/New_York' precludes 'America/New_York/Bronx'. It gives more reasons for the 1970 cutoff. It now mentions which time_t variants are supported, such as signed integer time_t. (Thanks to Paul Goyette for reporting typos in an experimental version of this change.) (Thanks to Philip Newton for correcting typos in these changes.) Documentation and commentary is more careful to distinguish UT in general from UTC in particular. (Thanks to Steve Allen.) Add a better source for the Zurich 1894 transition. (Thanks to Pierre-Yves Berger.) Update shapefile citations in tz-link.htm. (Thanks to Guy Harris.) Here are links to the release files: ftp://ftp.iana.org/tz/releases/tzcode2013e.tar.gz ftp://ftp.iana.org/tz/releases/tzdata2013e.tar.gz The files are also available via HTTP as follows: http://www.iana.org/time-zones/repository/releases/tzcode2013e.tar.gz http://www.iana.org/time-zones/repository/releases/tzdata2013e.tar.gz Each release file has a GPG signature, which can be retrieved by appending ".asc" to the above URLs. Copies of these signatures are appended to this message. As usual, links to the latest release files are here: http://www.iana.org/time-zones/repository/tzcode-latest.tar.gz http://www.iana.org/time-zones/repository/tzdata-latest.tar.gz ftp://ftp.iana.org/tz/tzcode-latest.tar.gz ftp://ftp.iana.org/tz/tzdata-latest.tar.gz This release corresponds to commit db6270a00d1a364865f3080ac41d8d6d42f5c833 dated Thu Sep 19 23:50:04 2013 -0700 in the unofficial github repository at <https://github.com/eggert/tz>. 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McMurdo/South Pole
by Stephen Colebourne Sept. 23, 2013

Sept. 23, 2013

Since McMurdo was not founded until 16 Feb 1956 (wikipedia), I think that it is simply incorrect data to assign any time-zone transitions until that date. There simply were no DST transitions in McMurdo in the 1930s as it did not exist. https://github.com/jodastephen/tzdiff/commit/57aac13605f184a46f74d22f7dddc9… This is a a case where an ID that has existed for a long time with reasonably good data that has now been degraded through a Zone to Link conversion. Stephen (I hadn't realised the extent of the data pollution of McMurdo until I did my recent data analysis)

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Deep Impact: worng time zone?
by Arthur David Olson Sept. 23, 2013

Sept. 23, 2013

"...analysis has uncovered a potential problem with computer time tagging..." "NASA's Deep Space Comet Hunter Mission Comes to an End" http://www.jpl.nasa.gov/news/news.php?release=2013-287 --ado

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A New Rule? (was McMurdo/South Pole)
by Bill Seymour Sept. 22, 2013

Sept. 22, 2013

A partly-baked idea to solve the more general problem of when zones appear and disappear: would it make sense to have another kind of entry in the zone RULES column to indicate that we should now follow another zone's practice? How about the keyword, Zone, a space, and the name of the other zone, with the next column following whitespace, if present, being the [UNTIL] column?

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Re: [tz] draft of change summary for next tz release
by David Patte ₯ Sept. 21, 2013

Sept. 21, 2013

And some of us prefer having at least one zone for each ISO 3166-1 country. Several of us understood the old theory file to require this. 1970 is an arbitrary computer geek cutoff point, with not much meaning to general time zone history.

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Jordan permanently on UTC+3?
by Paul Eggert Sept. 20, 2013

Sept. 20, 2013

I looked for hints about what Jordan's going to do with its clocks next month, and found this article from February: Cancelling winter saved Jordan $7 million Petra News Agency 2013-02-20 11:34 UTC http://www.albawaba.com/business/jordan-winter-electricity--472005 Currently the tz database is guessing that Jordan will revert to UTC+2 next month, but if this article is any indication they'll stay at UTC+3 indefinitely, which means the obvious tz patch (already mentioned in the 2012-10-15 comments) would be appropriate.

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Tocantins in Brazil probably not observing DST this season
by Steffen Thorsen Sept. 20, 2013

Sept. 20, 2013

According to this article, Tocantins in Brazil is very likely not to observe DST from October. The decree has not yet been issued, so the decision may still be revoked, but we assume it is very likely because it has been announced by the congressman and DST is so unpopular there. http://conexaoto.com.br/2013/09/18/ministerio-confirma-que-tocantins-esta-f… We will keep this article updated when this is confirmed: http://www.timeanddate.com/news/time/brazil-starts-dst-2013.html Best regards, Steffen Thorsen - timeanddate.com

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Getting close to new release: testing, testing, ...
by Paul Eggert Sept. 20, 2013

Sept. 20, 2013

We need to release a new version soon, because of Fiji. I did further testing and it appears that the recent changes to add meta-information to the zic output won't fly, because they're incompatible with the GNU C library on Ubuntu 12.04. So we need to rethink that feature. There's no rush to introduce it, so let's omit it from the next release. Also, the -t option recently added to tzselect seems like it will be superseded by the tzwinnow approach, whenever we get that working and stable, so for now I think I'd rather omit this. There are a few other problems found by "make public", mostly links that were in the wrong files. I'll post proposed changes soon. If other people could do some testing that'd be nice. You can run "make public". The output should contain the following diagnostics: warning: "antarctica", line 318: Antarctica/Palmer: pre-2013 clients may mishandle distant timestamps warning: "asia", line 1412: 24:00 not handled by pre-1998 versions of zic warning: "asia", line 2332: 24:00 not handled by pre-1998 versions of zic warning: "asia", line 1026: Asia/Jerusalem: pre-2013 clients may mishandle distant timestamps (rule from "asia", line 1021) warning: "asia", line 1315: Asia/Amman: pre-1994 clients may mishandle distant timestamps warning: "asia", line 2016: Asia/Gaza: pre-2013 clients may mishandle distant timestamps warning: "asia", line 2347: Asia/Hebron: pre-2013 clients may mishandle distant timestamps warning: "australasia", line 269: Pacific/Fiji: pre-2013 clients may mishandle distant timestamps warning: "europe", line 998: America/Godthab: pre-2013 clients may mishandle distant timestamps warning: "southamerica", line 1141: America/Santiago: pre-2013 clients may mishandle distant timestamps warning: "southamerica", line 1313: Pacific/Easter: pre-2013 clients may mishandle distant timestamps along with a very long section that starts as follows, which shows that the tz code is still broken on platforms with unsigned 32-bit time_t (this is a longstanding problem). checking uint32_t zones ... --- tzpublic/int64_t.out 2013-09-11 02:43:50.871343089 -0700 +++ tzpublic/uint32_t.out 2013-09-11 02:43:55.907343185 -0700 @@ -210,278 +210,6 @@ Europe/Andorra Sun Mar 29 01:00:00 2037 UT = Sun Mar 29 03:00:00 2037 CEST isdst=1 Europe/Andorra Sun Oct 25 00:59:59 2037 UT = Sun Oct 25 02:59:59 2037 CEST isdst=1 Europe/Andorra Sun Oct 25 01:00:00 2037 UT = Sun Oct 25 02:00:00 2037 CET isdst=0 -Europe/Andorra Sun Mar 28 00:59:59 2038 UT = Sun Mar 28 01:59:59 2038 CET isdst=0 -Europe/Andorra Sun Mar 28 01:00:00 2038 UT = Sun Mar 28 03:00:00 2038 CEST isdst=1 -Europe/Andorra Sun Oct 31 00:59:59 2038 UT = Sun Oct 31 02:59:59 2038 CEST isdst=1

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Historical data
by David Braverman Sept. 20, 2013

Sept. 20, 2013

I've followed the discussions about historical data with interest. I would like to keep historical data in the tzdb, and I understand why I'm in the minority. But I wonder if there couldn't be a compromise? We've implemented a .NET library that uses the tzdb by interpreting[1] the database rather than by compiling it. So for us, we only deploy the tzdb text files that the customer cares about. Some customers are strictly North American concerns, so we only put the northamerica file in their configuration; others need the whole database of 500-some zones. I think other posters have suggested separating pre-1970 data out into a separate file or file set. This would be perfect for our implementation. For the zic implementation, it seems like compilation is an all-or-nothing deal right now. But would it be difficult to create a build script that includes the historical data to the zic package if someone needs it, in addition to the post-1970 build script? Sorry if the question seems naïve. I just think there's room to compromise here. David Braverman Inner Drive Technology Chicago [1] The tzdb files actually get compiled down to an intermediate set of objects at application start, then live on in a singleton. The process takes about a second on an Azure Extra-Small instance. More info here: https://www.inner-drive.com/Demo/Timezones.aspx

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Data changes for v2013e
by Stephen Colebourne Sept. 20, 2013

Sept. 20, 2013

To better help everyone understand the data changes in 2013e, I've run a tool to analyse them and produce nice coloured git diffs. Changes from 2013d to 2013e https://github.com/jodastephen/tzdiff/commit/57aac13605f184a46f74d22f7dddc9… Lines in green are new added data, lines in red are deletions. >From a purely data perspective, the majority of 2013e changes are LMT based. The largest change is to McMurdo/South_Pole. Previous changes for reference: Changes from 2013c to 2013d https://github.com/jodastephen/tzdiff/commit/db93687fe0d5a6bb4a8ee9dd2d81e9… Changes from 2013b to 2013c https://github.com/jodastephen/tzdiff/commit/d145f2ae94c0587aba378920b44227… Changes from 2013a to 2013b https://github.com/jodastephen/tzdiff/commit/639b044db3e3c24d98b0cf5a6fba85… Stephen

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