Branch: Tag:

2018-09-05

2018-09-05 12:35:43 by Henrik Grubbström (Grubba) <grubba@grubba.org>

Calendar: Revert broken tzdata change in previous commit.

1:   News for the tz database    + Release 2018e - 2018-05-01 23:42:51 -0700 +  +  Briefly: +  +  North Korea switches back to +09 on 2018-05-05. +  The main format uses negative DST again, for Ireland etc. +  'make tarballs' now also builds a rearguard tarball. +  New 's' and 'd' suffixes in SAVE columns of Rule and Zone lines. +  +  Changes to past and future time stamps +  +  North Korea switches back from +0830 to +09 on 2018-05-05. +  (Thanks to Kang Seonghoon, Arthur David Olson, Seo Sanghyeon, +  and Tim Parenti.) +  +  Bring back the negative-DST changes of 2018a, except be more +  compatible with data parsers that do not support negative DST. +  Also, this now affects historical time stamps in Namibia and the +  former Czechoslovakia, not just Ireland. The main format now uses +  negative DST to model time stamps in Europe/Dublin (from 1971 on), +  Europe/Prague (1946/7), and Africa/Windhoek (1994/2017). This +  does not affect UT offsets, only time zone abbreviations and the +  tm_isdst flag. Also, this does not affect rearguard or vanguard +  formats; effectively the main format now uses vanguard instead of +  rearguard format. Data parsers that do not support negative DST +  can still use data from the rearguard tarball described below. +  +  Changes to build procedure +  +  The command 'make tarballs' now also builds the tarball +  tzdataVERSION-rearguard.tar.gz, which is like tzdataVERSION.tar.gz +  except that it uses rearguard format intended for trailing-edge +  data parsers. +  +  Changes to data format and to code +  +  The SAVE column of Rule and Zone lines can now have an 's' or 'd' +  suffix, which specifies whether the adjusted time is standard time +  or daylight saving time. If no suffix is given, daylight saving +  time is used if and only if the SAVE column is nonzero; this is +  the longstanding behavior. Although this new feature is not used +  in tzdata, it could be used to specify the legal time in Namibia +  1994-2017, as opposed to the popular time (see below). +  +  Changes to past time stamps +  +  From 1994 through 2017 Namibia observed DST in winter, not summer. +  That is, it used negative DST, as Ireland still does. This change +  does not affect UTC offsets; it affects only the tm_isdst flag and +  the abbreviation used during summer, which is now CAT, not WAST. +  Although (as noted by Michael Deckers) summer and winter time were +  both simply called "standard time" in Namibian law, in common +  practice winter time was considered to be DST (as noted by Stephen +  Colebourne). The full effect of this change is only in vanguard +  format; in rearguard and main format, the tm_isdst flag is still +  zero in winter and nonzero in summer. +  +  In 1946/7 Czechoslovakia also observed negative DST in winter. +  The full effect of this change is only in vanguard format; in +  rearguard and main formats, it is modeled as plain GMT without +  daylight saving. Also, the dates of some 1944/5 DST transitions +  in Czechoslovakia have been changed. +  +  + Release 2018d - 2018-03-22 07:05:46 -0700 +  +  Briefly: +  +  Palestine starts DST a week earlier in 2018. +  Add support for vanguard and rearguard data consumers. +  Add subsecond precision to source data format, though not to data. +  +  Changes to future time stamps +  +  In 2018, Palestine starts DST on March 24, not March 31. +  Adjust future predictions accordingly. (Thanks to Sharef Mustafa.) +  +  Changes to past and future time stamps +  +  Casey Station in Antarctica changed from +11 to +08 on 2018-03-11 +  at 04:00. (Thanks to Steffen Thorsen.) +  +  Changes to past time stamps +  +  Historical transitions for Uruguay, represented by +  America/Montevideo, have been updated per official legal documents, +  replacing previous data mainly originating from the inventions of +  Shanks & Pottenger. This has resulted in adjustments ranging from +  30 to 90 minutes in either direction over at least two dozen +  distinct periods ranging from one day to several years in length. +  A mere handful of pre-1991 transitions are unaffected; data since +  then has come from more reliable contemporaneous reporting. These +  changes affect various timestamps in 1920-1923, 1936, 1939, +  1942-1943, 1959, 1966-1970, 1972, 1974-1980, and 1988-1990. +  Additionally, Uruguay's pre-standard-time UT offset has been +  adjusted westward by 7 seconds, from UT-03:44:44 to UT-03:44:51, to +  match the location of the Observatory of the National Meteorological +  Institute in Montevideo. +  (Thanks to Jeremie Bonjour, Tim Parenti, and Michael Deckers.) +  +  Enderbury and Kiritimati skipped New Year's Eve 1994, not +  New Year's Day 1995. (Thanks to Kerry Shetline.) +  +  Fix the 1912-01-01 transition for Portugal and its colonies. +  This transition was at 00:00 according to the new UT offset, not +  according to the old one. Also assume that Cape Verde switched on +  the same date as the rest, not in 1907. This affects +  Africa/Bissau, Africa/Sao_Tome, Asia/Macau, Atlantic/Azores, +  Atlantic/Cape_Verde, Atlantic/Madeira, and Europe/Lisbon. +  (Thanks to Michael Deckers.) +  +  Fix an off-by-1 error for pre-1913 timestamps in Jamaica and in +  Turks & Caicos. +  +  Changes to past time zone abbreviations +  +  MMT took effect in Uruguay from 1908-06-10, not 1898-06-28. There +  is no clock change associated with the transition. +  +  Changes to build procedure +  +  The new DATAFORM macro in the Makefile lets the installer choose +  among three source data formats. The idea is to lessen downstream +  disruption when data formats are improved. +  +  * DATAFORM=vanguard installs from the latest, bleeding-edge +  format. DATAFORM=main (the default) installs from the format +  used in the 'africa' etc. files. DATAFORM=rearguard installs +  from a trailing-edge format. Eventually, elements of today's +  vanguard format should move to the main format, and similarly +  the main format's features should eventually move to the +  rearguard format. +  +  * In the current version, the main and rearguard formats are +  identical and match that of 2018c, so this change does not +  affect default behavior. The vanguard format currently contains +  one feature not in the main format: negative SAVE values. This +  improves support for Ireland, which uses Irish Standard Time +  (IST, UTC+01) in summer and GMT (UTC) in winter. tzcode has +  supported negative SAVE values for decades, and this feature +  should move to the main format soon. However, it will not move +  to the rearguard format for quite some time because some +  downstream parsers do not support it. +  +  * The build procedure constructs three files vanguard.zi, main.zi, +  and rearguard.zi, one for each format. The files represent the +  same data as closely as the formats allow. These three files +  are intended for downstream data consumers and are not +  installed. Zoneinfo parsers that do not support negative SAVE values +  should start using rearguard.zi, so that they will be unaffected +  when the negative-DST feature moves from vanguard to main. +  Bleeding-edge Zoneinfo parsers that support the new features +  already can use vanguard.zi; in this respect, current tzcode is +  bleeding-edge. +  +  The Makefile should now be safe for parallelized builds, and 'make +  -j to2050new.tzs' is now much faster on a multiprocessor host +  with GNU Make. +  +  When built with -DSUPPRESS_TZDIR, the tzcode library no longer +  prepends TZDIR/ to file names that do not begin with '/'. This is +  not recommended for general use, due to its security implications. +  (From a suggestion by Manuela Friedrich.) +  +  Changes to code +  +  zic now accepts subsecond precision in expressions like +  00:19:32.13, which is approximately the legal time of the +  Netherlands from 1835 to 1937. However, because it is +  questionable whether the few recorded uses of non-integer offsets +  had subsecond precision in practice, there are no plans for tzdata +  to use this feature. (Thanks to Steve Allen for pointing out +  the limitations of historical data in this area.) +  +  The code is a bit more portable to MS-Windows. Installers can +  compile with -DRESERVE_STD_EXT_IDS on MS-Windows platforms that +  reserve identifiers like 'localtime'. (Thanks to Manuela +  Friedrich). +  +  Changes to documentation and commentary +  +  theory.html now outlines tzdb's extensions to POSIX's model for +  civil time, and has a section "POSIX features no longer needed" +  that lists POSIX API components that are now vestigial. +  (From suggestions by Steve Summit.) It also better distinguishes +  time zones from tz regions. (From a suggestion by Guy Harris.) +  +  Commentary is now more consistent about using the phrase "daylight +  saving time", to match the C name tm_isdst. Daylight saving time +  need not occur in summer, and need not have a positive offset from +  standard time. +  +  Commentary about historical transitions in Uruguay has been expanded +  with links to many relevant legal documents. +  (Thanks to Tim Parenti.) +  +  Commentary now uses some non-ASCII characters with Unicode value +  less than U+0100, as they can be useful and should work even with +  older editors such as XEmacs. +  +  + Release 2018c - 2018-01-22 23:00:44 -0800 +  +  Briefly: +  Revert Irish changes that relied on negative SAVE values. +  +  Changes to tm_isdst +  +  Revert the 2018a change to Europe/Dublin. As before, this change +  does not affect UT offsets or abbreviations; it affects only +  whether timestamps are considered to be standard time or +  daylight-saving time, as expressed in the tm_isdst flag of C's +  struct tm type. This reversion is intended to be a temporary +  workaround for problems discovered with downstream uses of +  releases 2018a and 2018b, which implemented Irish time by using +  negative SAVE values in the Eire rules of the 'europe' file. +  Although negative SAVE values have been part of tzcode for many +  years and are supported by many platforms, they were not +  documented before 2018a and ICU and OpenJDK do not currently +  support them. A mechanism to export data to platforms lacking +  support for negative DST is planned to be developed before the +  change is reapplied. (Problems reported by Deborah Goldsmith and +  Stephen Colebourne.) +  +  Changes to past time stamps +  +  Japanese DST transitions (1948-1951) were Sundays at 00:00, not +  Saturdays or Sundays at 02:00. (Thanks to Takayuki Nikai.) +  +  Changes to build procedure +  +  The build procedure now works around mawk 1.3.3's lack of support +  for character class expressions. (Problem reported by Ohyama.) +  +  + Release 2018b - 2018-01-17 23:24:48 -0800 +  +  Briefly: +  Fix a packaging problem in tz2018a, which was missing 'pacificnew'. +  +  Changes to build procedure +  +  The distribution now contains the file 'pacificnew' again. +  This file was inadvertantly omitted in the 2018a distribution. +  (Problem reported by Matias Fonzo.) +  +  + Release 2018a - 2018-01-12 22:29:21 -0800 +  +  Briefly: +  São Tomé and Príncipe switched from +00 to +01. +  Brazil's DST will now start on November's first Sunday. +  Ireland's standard time is now in the summer, not the winter. +  Use Debian-style installation locations, instead of 4.3BSD-style. +  New zic option -t. +  +  Changes to past and future time stamps +  +  São Tomé and Príncipe switched from +00 to +01 on 2018-01-01 at +  01:00. (Thanks to Steffen Thorsen and Michael Deckers.) +  +  Changes to future time stamps +  +  Starting in 2018 southern Brazil will begin DST on November's +  first Sunday instead of October's third Sunday. (Thanks to +  Steffen Thorsen.) +  +  Changes to past time stamps +  +  A discrepancy of 4 s in timestamps before 1931 in South Sudan has +  been corrected. The 'backzone' and 'zone.tab' files did not agree +  with the 'africa' and 'zone1970.tab' files. (Problem reported by +  Michael Deckers.) +  +  The abbreviation invented for Bolivia Summer Time (1931-2) is now +  BST instead of BOST, to be more consistent with the convention +  used for Latvian Summer Time (1918-9) and for British Summer Time. +  +  Changes to tm_isdst +  +  Change Europe/Dublin so that it observes Irish Standard Time (UT +  +01) in summer and GMT (as negative daylight-saving) in winter, +  instead of observing standard time (GMT) in winter and Irish +  Summer Time (UT +01) in summer. This change does not affect UT +  offsets or abbreviations; it affects only whether timestamps are +  considered to be standard time or daylight-saving time, as +  expressed in the tm_isdst flag of C's struct tm type. +  (Discrepancy noted by Derick Rethans.) +  +  Changes to build procedure +  +  The default installation locations have been changed to mostly +  match Debian circa 2017, instead of being designed as an add-on to +  4.3BSD circa 1986. This affects the Makefile macros TOPDIR, +  TZDIR, MANDIR, and LIBDIR. New Makefile macros TZDEFAULT, USRDIR, +  USRSHAREDIR, BINDIR, ZDUMPDIR, and ZICDIR let installers tailor +  locations more precisely. (This responds to suggestions from +  Brian Inglis and from Steve Summit.) +  +  The default installation procedure no longer creates the +  backward-compatibility link US/Pacific-New, which causes +  confusion during user setup (e.g., see Debian bug 815200). +  Use 'make BACKWARD="backward pacificnew"' to create the link +  anyway, for now. Eventually we plan to remove the link entirely. +  +  tzdata.zi now contains a version-number comment. +  (Suggested by Tom Lane.) +  +  The Makefile now quotes values like BACKWARD more carefully when +  passing them to the shell. (Problem reported by Zefram.) +  +  Builders no longer need to specify -DHAVE_SNPRINTF on platforms +  that have snprintf and use pre-C99 compilers. (Problem reported +  by Jon Skeet.) +  +  Changes to code +  +  zic has a new option -t FILE that specifies the location of the +  file that determines local time when TZ is unset. The default for +  this location can be configured via the new TZDEFAULT makefile +  macro, which defaults to /etc/localtime. +  +  Diagnostics and commentary now distinguish UT from UTC more +  carefully; see theory.html for more information about UT vs UTC. +  +  zic has been ported to GCC 8's -Wstringop-truncation option. +  (Problem reported by Martin Sebor.) +  +  Changes to documentation and commentary +  +  The zic man page now documents the longstanding behavior that +  times and years can be out of the usual range, with negative times +  counting backwards from midnight and with year 0 preceding year 1. +  (Problem reported by Michael Deckers.) +  +  The theory.html file now mentions the POSIX limit of six chars +  per abbreviation, and lists alphabetic abbreviations used. +  +  The files tz-art.htm and tz-link.htm have been renamed to +  tz-art.html and tz-link.html, respectively, for consistency with +  other file names and to simplify web server configuration. +  +    Release 2017c - 2017-10-20 14:49:34 -0700       Briefly:
758:    Comments in zone tables have been improved. (Thanks to J William Piggott.)       tzselect again limits its menu comments so that menus fit on a -  24x80 alphanumeric display. +  24×80 alphanumeric display.       A new web page tz-how-to.html. (Thanks to Bill Seymour.)   
895:    (Thanks to Jon Skeet and Arthur David Olson.) Constraints on    simultaneity are now documented.    -  The two characters '%z' in a zone format now stand for the UTC -  offset, e.g., '-07' for seven hours behind UTC and '+0530' for +  The two characters '%z' in a zone format now stand for the UT +  offset, e.g., '-07' for seven hours behind UT and '+0530' for    five hours and thirty minutes ahead. This better supports time    zone abbreviations conforming to POSIX.1-2001 and later.   
1019:    The spring 1988 transition was 1988-10-09, not 1988-10-02.    The fall 1990 transition was 1990-03-11, not 1990-03-18.    -  Assume no UTC offset change for Pacific/Easter on 1890-01-01, +  Assume no UT offset change for Pacific/Easter on 1890-01-01,    and omit all transitions on Pacific/Easter from 1942 through 1946    since we have no data suggesting that they existed.       One more zone has been turned into a link, as it differed    from an existing zone only for older time stamps. As usual, -  this change affects UTC offsets in pre-1970 time stamps only. +  this change affects UT offsets in pre-1970 time stamps only.    The zone's old contents have been moved to the 'backzone' file.    The affected zone is America/Montreal.   
1055:       Some more zones have been turned into links, when they differed    from existing zones only for older time stamps. As usual, -  these changes affect UTC offsets in pre-1970 time stamps only. +  these changes affect UT offsets in pre-1970 time stamps only.    Their old contents have been moved to the 'backzone' file.    The affected zones are: America/Antigua, America/Cayman,    Pacific/Midway, and Pacific/Saipan.
1107:       Some more zones have been turned into links, when they differed    from existing zones only for older time stamps. As usual, -  these changes affect UTC offsets in pre-1970 time stamps only. +  these changes affect UT offsets in pre-1970 time stamps only.    Their old contents have been moved to the 'backzone' file.    The affected zones are: Asia/Aden, Asia/Bahrain, Asia/Kuwait,    and Asia/Muscat.
1154:       Some more zones have been turned into links, when they differed    from existing zones only for older time stamps. As usual, -  these changes affect UTC offsets in pre-1970 time stamps only. +  these changes affect UT offsets in pre-1970 time stamps only.    Their old contents have been moved to the 'backzone' file.    The affected zones are: Africa/Addis_Ababa, Africa/Asmara,    Africa/Dar_es_Salaam, Africa/Djibouti, Africa/Kampala,
1244:       Some more zones have been turned into links, when they differed    from existing zones only for older timestamps. As usual, -  these changes affect UTC offsets in pre-1970 timestamps only. +  these changes affect UT offsets in pre-1970 timestamps only.    Their old contents have been moved to the 'backzone' file.    The affected zones are: Africa/Blantyre, Africa/Bujumbura,    Africa/Gaborone, Africa/Harare, Africa/Kigali, Africa/Lubumbashi,
1329:       Some more zones have been turned into links, when they differed    from existing zones only for older timestamps. As usual, -  these changes affect UTC offsets in pre-1970 timestamps only. +  these changes affect UT offsets in pre-1970 timestamps only.    Their old contents have been moved to the 'backzone' file.    The affected zones are: Africa/Bangui, Africa/Brazzaville,    Africa/Douala, Africa/Kinshasa, Africa/Libreville, Africa/Luanda,
1479:    standard and daylight saving time the abbreviations are AEST and AEDT    instead of the former EST for both; similarly, ACST/ACDT, ACWST/ACWDT,    and AWST/AWDT are now used instead of the former CST, CWST, and WST. -  This change does not affect UTC offsets, only time zone abbreviations. +  This change does not affect UT offsets, only time zone abbreviations.    (Thanks to Rich Tibbett and many others.)       Asia/Novokuznetsk shifts from NOVT to KRAT (remaining on UT +07)
1516:    Treindl sent helpful translations of two papers by Guo Qingsheng.)       Some zones have been turned into links, when they differed from existing -  zones only for older UTC offsets where data entries were likely invented. -  These changes affect UTC offsets in pre-1970 timestamps only. This is +  zones only for older UT offsets where data entries were likely invented. +  These changes affect UT offsets in pre-1970 timestamps only. This is    similar to the change in release 2013e, except this time for western    Africa. The affected zones are: Africa/Bamako, Africa/Banjul,    Africa/Conakry, Africa/Dakar, Africa/Freetown, Africa/Lome,