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  1. JDK
  2. JDK-8200359

(tz) Upgrade time-zone data to tzdata2018d


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        [Fri Mar 23 22:09:23 UTC 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:


           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

             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

           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:


        Links are also available via plain HTTP, and via FTP from
        ftp://ftp.iana.org/tz/releases with the same basenames as above.


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                • Assignee:
                  rpatil Ramanand Patil
                  rpatil Ramanand Patil
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