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March 2018

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2018d release of tz code and data available
by Paul Eggert March 23, 2018

March 23, 2018

The 2018d release of the tz code and data is available. It reflects the following changes, which were either circulated on the tz mailing list or are relatively minor technical or administrative changes: 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 Portugual 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. Here are links to the release files: https://www.iana.org/time-zones/repository/releases/tzcode2018d.tar.gz https://www.iana.org/time-zones/repository/releases/tzdata2018d.tar.gz https://www.iana.org/time-zones/repository/releases/tzdb-2018d.tar.lz As usual, links to the latest release files are here: https://www.iana.org/time-zones/repository/tzcode-latest.tar.gz https://www.iana.org/time-zones/repository/tzdata-latest.tar.gz https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz Links are also available via plain HTTP, and via FTP from ftp://ftp.iana.org/tz/releases with the same basenames as above. 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. This release corresponds to commit bd850bce5d292caaa5eba2c2088f6d4ad8024647 dated 2018-03-22 07:05:46 -0700 and tagged '2018d' in the development GitHub repository at <https://github.com/eggert/tz>. Here are the SHA-512 checksums for the release files: e79a95e235cd384247e4112d5154f30eb7b40f28dab4872ed9153e45bf56569949d0845bc1b9ad24b7a5f9609bdadfc892959dbf0d540dbca79b18398dc4f930 tzcode2018d.tar.gz ee961aedc34e134172523a29fb8a9358f42649d06ffcd2d8a6ad86eeb174a80af5bfc4637e9e52ecdc51fa3d01afef9fff660a69ed72904ff747a59b5634830b tzdata2018d.tar.gz 12c839846c147b83ace915e399fe447f93e83b500327fb4549b6039615f548d7167594168b5c4779ee1f33d7a1b8c2e294aa13cd35823d778617065ad9ad8ea5 tzdb-2018d.tar.lz Here are the GPG checksums for the release files: -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAABAgAGBQJas7pNAAoJEO2X6Q5iqn40dn8P+gI1f6sWKcA8iuDkRWundwBk Y92iYPChJDbgUSiWw3o+qyFmVUz0P1PZkB3rCTFhtyY8u6zCiO4+6xADyS+le3II iwwIg2yCqPxBXDXYkcFvSrXDuOo1hG009L1k9nKmv6RvO7lvr/o0K/pRQTWKiV2w jS9gPZeZ/ggTdcyaD9tzFNwDe0nCg54rwFs3Gy+YK2+8fNhLmYJCp3WJydza9zgU pBMMP868h1ZY9uWEZcWX3mstyKD4egFRfyHMj4XPVrnGwpMT5u7groiq2TZv/MXV A/HDxa4jU+El6RW0TwAVnGEwUSJ3L3I7B6/Pbf3jf+VCTYkw67cX/WrtSNop1E03 ujPZVqYr5N8HLu/VO/R2R+OccvMZ1X/URehA4068w/+ESG8X8AbRVBYGavpFmnUv uHOeOFgzcJUQqFU1fqAEdhlrYqqbnsRFJN8QX1QWwQs5fUAzNSAkAB+kTEVCAvhK 1xaxlNaZqoWqT0bYvD2TL+VLkPNHvu8RMpa/rhmjE23AWfYuSJsAABNMBpB5t6ux SbBOBeJ+a5a1rZwya0hxeX6A3BCBPXKBjnt8MjBnV1s8Ns4Ng7jQ5ZqOXtlSo4ER fYHbVQITXnE+DbuM1zF6RY1dwmCLvkxpdM5lifgiYCdcDzttsifDdrq5WM+pJsz5 3yTFJFsk6et2ekpHRugZ =MMy8 -----END PGP SIGNATURE----- -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAABAgAGBQJas7pNAAoJEO2X6Q5iqn40BqwP/A8PU9mzxssBdQirWsuGhN3E +3hk6i7UFLrCHixbpN03y7r8ujkhRvkjLSrA2tcrYEK9t8NLkhQIrnmlVjEOQEcz +qiZWJV55kd2dhk2EE+pc8xXuqRsnId4r/xCF+D2wxl6IZpMEFelRCRiCGgszhDS FSv3UjlnpBv3uB5UgKdOFJKYcTvfOZ5jmpt1O6Ma9YNxqlc2+s8hUBR3VEtzancU +AyCoL/sUrijfGOZPSznhGJJ3lC5LkjkWqC0BYB5EI3YeClVtGWoZlD64jShJhWT pe3CAimaEibz1ty1tGz4Agdd0vQErvyCPQY6wy1pRYPW5wb++JomMVub7Uh7w/6o pvrkVaVqeiWeENoI6NRnmC+ANSaz6/lF61HM36VZ1XaCgmeCDaLHn31WKHRPctse r26++PyCIJwllaTNfGynjkAKUeBJJwwR8a/sjPeqEfEgoDKV1EpQVCBbPna3hmTq 8nzt11WsTNG+aocYr3hevSYiyxEWOLp5O9UaiTtVDc91Mhk2U9E9Fa7Zva35ZhjJ oRPS+AU5GFfWzgiW8XOLURqvwRNqUUudNaXy2wVuzwROdmboyewzB//MBavkI+r+ raI+coG2ZJoPcQmuRCUcjs1+JnNBL3sZT68/jTy2w0LURfUP9V+dUuJgjtRbMCtb Myzq3RCYNI/x3EjU/xcb =ibli -----END PGP SIGNATURE----- -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAABAgAGBQJas7pOAAoJEO2X6Q5iqn40ursP/02PBDqd4eb8qrKrjScYt+I4 wnXMcjy9AmsfhPq1k1x6ZUI5qIbidrMD9S9m4NwKBGyvGxxcneWWJ5Yoln+K95YJ tCtm40eHypeVUlsXJExv3JB0hJ7d7eY2olbY/DcK6CTYt7R4amGU/ClCQpEIVTz2 HcVeH8oOPRUG0STyzKh2lPF0Wua6LUGp9/nZWgsETsXrAQ8MaC/vlyrjiEJsvwP1 65bOoNiRKiGU7tp6JhFE8v85vLKgkzmHeysWJdMt0aczH1DMwlSWS9ViEauLugK7 K0ERNC22WwEzya0EKmTMcRFHYIT1B9/dg0Tbb2h2KKRqu7kzd2NVr6ap5Cu6ezYO hThz6i09OL6ADSwSk4c6JeUUjX7rGG6DNu0pCQYlNJ9xIhi+U/FAuTvzBfU3uJe3 8akO1UGwUWA/TwtnQTv08uGGia+Wt/GbQStkidZFVvdbXcjSH39GlhRXRWDKSOCv wDVNMkopDQOsxwoFgAE45dacQZh2Qv29eT4pG6Eo2J+eXJR2lb5edQkDZNLk2DcE 6frcVchrdBeaUUSA1+ssH3B+hVwwJ7IX/FCwhKDZgxyy67oqGVChkeUjes4GJ5vB 0t7/XZTORvsH6XwBNDKoXS0fswtZiwhPr3YV1nZHwKCa0OWIs9WsPt587K82Hlsf mROMmzivSut43pdALRCr =zKoc -----END PGP SIGNATURE-----

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