• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1News for the tz database
2
3Unreleased, experimental changes
4
5  Changes to build procedure
6
7    Files in distributed tarballs now have correct commit times.
8    Formerly, the committer's time zone was incorrectly ignored.
9
10    Distribution products (*.asc, *.gz, and *.lz) now have
11    reproducible timestamps.  Formerly, only the contents of the
12    compressed tarballs had reproducible timestamps.
13
14  Changes to commentary
15
16    The leapseconds file contains commentary about the IERS and NIST
17    last-modified and expiration timestamps for leap second data.
18    (Thanks to Judah Levine.)
19
20
21Release 2025b - 2025-03-22 13:40:46 -0700
22
23  Briefly:
24    New zone for Aysén Region in Chile which moves from -04/-03 to -03.
25
26  Changes to future timestamps
27
28    Chile's Aysén Region moves from -04/-03 to -03 year-round, joining
29    Magallanes Region.  The region will not change its clocks on
30    2025-04-05 at 24:00, diverging from America/Santiago and creating a
31    new zone America/Coyhaique.  (Thanks to Yonathan Dossow.)  Model
32    this as a change to standard offset effective 2025-03-20.
33
34  Changes to past timestamps
35
36    Iran switched from +04 to +0330 on 1978-11-10 at 24:00, not at
37    year end.  (Thanks to Roozbeh Pournader.)
38
39  Changes to code
40
41    'zic -l TIMEZONE -d . -l /some/other/file/system' no longer
42    attempts to create an incorrect symlink, and no longer has a
43    read buffer underflow.  (Problem reported by Evgeniy Gorbanev.)
44
45
46Release 2025a - 2025-01-15 10:47:24 -0800
47
48  Briefly:
49    Paraguay adopted permanent -03 starting spring 2024.
50    Improve pre-1991 data for the Philippines.
51    Etc/Unknown is now reserved.
52
53  Changes to future timestamps
54
55    Paraguay stopped changing its clocks after the spring-forward
56    transition on 2024-10-06, so it is now permanently at -03.
57    (Thanks to Heitor David Pinto and Even Scharning.)
58    This affects timestamps starting 2025-03-22, as well as the
59    obsolescent tm_isdst flags starting 2024-10-15.
60
61  Changes to past timestamps
62
63    Correct timestamps for the Philippines before 1900, and from 1937
64    through 1990.  (Thanks to P Chan for the heads-up and citations.)
65    This includes adjusting local mean time before 1899; fixing
66    transitions in September 1899, January 1937, and June 1954; adding
67    transitions in December 1941, November 1945, March and September
68    1977, and May and July 1990; and removing incorrect transitions in
69    March and September 1978.
70
71  Changes to data
72
73    Add zone1970.tab lines for the Concordia and Eyre Bird Observatory
74    research stations.  (Thanks to Derick Rethans and Jule Dabars.)
75
76  Changes to code
77
78    strftime %s now generates the correct numeric string even when the
79    represented number does not fit into time_t.  This is better than
80    generating the numeric equivalent of (time_t) -1, as strftime did
81    in TZDB releases 96a (when %s was introduced) through 2020a and in
82    releases 2022b through 2024b.  It is also better than failing and
83    returning 0, as strftime did in releases 2020b through 2022a.
84
85    strftime now outputs an invalid conversion specifier as-is,
86    instead of eliding the leading '%', which confused debugging.
87
88    An invalid TZ now generates the time zone abbreviation "-00", not
89    "UTC", to help the user see that an error has occurred.  (Thanks
90    to Arthur David Olson for suggesting a "wrong result".)
91
92    mktime and timeoff no longer incorrectly fail merely because a
93    struct tm component near INT_MIN or INT_MAX overflows when a
94    lower-order component carries into it.
95
96    TZNAME_MAXIMUM, the maximum number of bytes in a proleptic TZ
97    string's time zone abbreviation, now defaults to 254 not 255.
98    This helps reduce the size of internal state from 25480 to 21384
99    on common platforms.  This change should not be a problem, as
100    nobody uses such long "abbreviations" and the longstanding tzcode
101    maximum was 16 until release 2023a.  For those who prefer no
102    arbitrary limits, you can now specify TZNAME_MAXIMUM values up to
103    PTRDIFF_MAX, a limit forced by C anyway; formerly tzcode silently
104    misbehaved unless TZNAME_MAXIMUM was less than INT_MAX.
105
106    tzset and related functions no longer leak a file descriptor if
107    another thread forks or execs at about the same time and if the
108    platform has O_CLOFORK and O_CLOEXEC respectively.  Also, the
109    functions no longer let a TZif file become a controlling terminal.
110
111    'zdump -' now reads TZif data from /dev/stdin.
112    (From a question by Arthur David Olson.)
113
114  Changes to documentation
115
116    The name Etc/Unknown is now reserved: it will not be used by TZDB.
117    This is for compatibility with CLDR, which uses the string
118    "Etc/Unknown" for an unknown or invalid timezone.  (Thanks to
119    Justin Grant, Mark Davis, and Guy Harris.)
120
121    Cite Internet RFC 9636, which obsoletes RFC 8536 for TZif format.
122
123
124Release 2024b - 2024-09-04 12:27:47 -0700
125
126  Briefly:
127    Improve historical data for Mexico, Mongolia, and Portugal.
128    System V names are now obsolescent.
129    The main data form now uses %z.
130    The code now conforms to RFC 8536 for early timestamps.
131    Support POSIX.1-2024, which removes asctime_r and ctime_r.
132    Assume POSIX.2-1992 or later for shell scripts.
133    SUPPORT_C89 now defaults to 1.
134
135  Changes to past timestamps
136
137    Asia/Choibalsan is now an alias for Asia/Ulaanbaatar rather than
138    being a separate Zone with differing behavior before April 2008.
139    This seems better given our wildly conflicting information about
140    Mongolia's time zone history.  (Thanks to Heitor David Pinto.)
141
142    Historical transitions for Mexico have been updated based on
143    official Mexican decrees.  The affected timestamps occur during
144    the years 1921-1927, 1931, 1945, 1949-1970, and 1981-1997.
145    The affected zones are America/Bahia_Banderas, America/Cancun,
146    America/Chihuahua, America/Ciudad_Juarez, America/Hermosillo,
147    America/Mazatlan, America/Merida, America/Mexico_City,
148    America/Monterrey, America/Ojinaga, and America/Tijuana.
149    (Thanks to Heitor David Pinto.)
150
151    Historical transitions for Portugal, represented by Europe/Lisbon,
152    Atlantic/Azores, and Atlantic/Madeira, have been updated based on a
153    close reading of old Portuguese legislation, replacing previous data
154    mainly originating from Whitman and Shanks & Pottenger.  These
155    changes affect a few transitions in 1917-1921, 1924, and 1940
156    throughout these regions by a few hours or days, and various
157    timestamps between 1977 and 1993 depending on the region.  In
158    particular, the Azores and Madeira did not observe DST from 1977 to
159    1981.  Additionally, the adoption of standard zonal time in former
160    Portuguese colonies have been adjusted: Africa/Maputo in 1909, and
161    Asia/Dili by 22 minutes at the start of 1912.
162    (Thanks to Tim Parenti.)
163
164  Changes to past tm_isdst flags
165
166    The period from 1966-04-03 through 1966-10-02 in Portugal is now
167    modeled as DST, to more closely reflect how contemporaneous changes
168    in law entered into force.
169
170  Changes to data
171
172    Names present only for compatibility with UNIX System V
173    (last released in the 1990s) have been moved to 'backward'.
174    These names, which for post-1970 timestamps mostly just duplicate
175    data of geographical names, were confusing downstream uses.
176    Names moved to 'backward' are now links to geographical names.
177    This affects behavior for TZ='EET' for some pre-1981 timestamps,
178    for TZ='CET' for some pre-1947 timestamps, and for TZ='WET' for
179    some pre-1996 timestamps.  Also, TZ='MET' now behaves like
180    TZ='CET' and so uses the abbreviation "CET" rather than "MET".
181    Those needing the previous TZDB behavior, which does not match any
182    real-world clocks, can find the old entries in 'backzone'.
183    (Problem reported by Justin Grant.)
184
185    The main source files' time zone abbreviations now use %z,
186    supported by zic since release 2015f and used in vanguard form
187    since release 2022b.  For example, America/Sao_Paulo now contains
188    the zone continuation line "-3:00 Brazil %z", which is less error
189    prone than the old "-3:00 Brazil -03/-02".  This does not change
190    the represented data: the generated TZif files are unchanged.
191    Rearguard form still avoids %z, to support obsolescent parsers.
192
193    Asia/Almaty has been removed from zonenow.tab as it now agrees
194    with Asia/Tashkent for future timestamps, due to Kazakhstan's
195    2024-02-29 time zone change.  Similarly, America/Scoresbysund
196    has been removed, as it now agrees with America/Nuuk due to
197    its 2024-03-31 time zone change.
198
199  Changes to code
200
201    localtime.c now always uses a TZif file's time type 0 to handle
202    timestamps before the file's first transition.  Formerly,
203    localtime.c sometimes inferred a different time type, in order to
204    handle problematic data generated by zic 2018e or earlier.  As it
205    is now safe to assume more recent versions of zic, there is no
206    longer a pressing need to fail to conform RFC 8536 section 3.2,
207    which requires using time type 0 in this situation.  This change
208    does not affect behavior when reading TZif files generated by zic
209    2018f and later.
210
211    POSIX.1-2024 removes asctime_r and ctime_r and does not let
212    libraries define them, so remove them except when needed to
213    conform to earlier POSIX.  These functions are dangerous as they
214    can overrun user buffers.  If you still need them, add
215    -DSUPPORT_POSIX2008 to CFLAGS.
216
217    The SUPPORT_C89 option now defaults to 1 instead of 0, fixing a
218    POSIX-conformance bug introduced in 2023a.
219
220    tzselect now supports POSIX.1-2024 proleptic TZ strings.  Also, it
221    assumes POSIX.2-1992 or later, as practical porting targets now
222    all support that, and it uses some features from POSIX.1-2024 if
223    available.
224
225  Changes to build procedure
226
227    'make check' no longer requires curl and Internet access.
228
229    The build procedure now assumes POSIX.2-1992 or later, to simplify
230    maintenance.  To build on Solaris 10, the only extant system still
231    defaulting to pre-POSIX, prepend /usr/xpg4/bin to PATH.
232
233  Changes to documentation
234
235    The documentation now reflects POSIX.1-2024.
236
237  Changes to commentary
238
239    Commentary about historical transitions in Portugal and her former
240    colonies has been expanded with links to relevant legislation.
241    (Thanks to Tim Parenti.)
242
243
244Release 2024a - 2024-02-01 09:28:56 -0800
245
246  Briefly:
247    Kazakhstan unifies on UTC+5 beginning 2024-03-01.
248    Palestine springs forward a week later after Ramadan.
249    zic no longer pretends to support indefinite-past DST.
250    localtime no longer mishandles Ciudad Juárez in 2422.
251
252  Changes to future timestamps
253
254    Kazakhstan unifies on UTC+5.  This affects Asia/Almaty and
255    Asia/Qostanay which together represent the eastern portion of the
256    country that will transition from UTC+6 on 2024-03-01 at 00:00 to
257    join the western portion.  (Thanks to Zhanbolat Raimbekov.)
258
259    Palestine springs forward a week later than previously predicted
260    in 2024 and 2025.  (Thanks to Heba Hamad.)  Change spring-forward
261    predictions to the second Saturday after Ramadan, not the first;
262    this also affects other predictions starting in 2039.
263
264  Changes to past timestamps
265
266    Asia/Ho_Chi_Minh's 1955-07-01 transition occurred at 01:00
267    not 00:00.  (Thanks to Đoàn Trần Công Danh.)
268
269    From 1947 through 1949, Toronto's transitions occurred at 02:00
270    not 00:00.  (Thanks to Chris Walton.)
271
272    In 1911 Miquelon adopted standard time on June 15, not May 15.
273
274  Changes to code
275
276    The FROM and TO columns of Rule lines can no longer be "minimum"
277    or an abbreviation of "minimum", because TZif files do not support
278    DST rules that extend into the indefinite past - although these
279    rules were supported when TZif files had only 32-bit data, this
280    stopped working when 64-bit TZif files were introduced in 1995.
281    This should not be a problem for realistic data, since DST was
282    first used in the 20th century.  As a transition aid, FROM columns
283    like "minimum" are now diagnosed and then treated as if they were
284    the year 1900; this should suffice for TZif files on old systems
285    with only 32-bit time_t, and it is more compatible with bugs in
286    2023c-and-earlier localtime.c.  (Problem reported by Yoshito
287    Umaoka.)
288
289    localtime and related functions no longer mishandle some
290    timestamps that occur about 400 years after a switch to a time
291    zone with a DST schedule.  In 2023d data this problem was visible
292    for some timestamps in November 2422, November 2822, etc. in
293    America/Ciudad_Juarez.  (Problem reported by Gilmore Davidson.)
294
295    strftime %s now uses tm_gmtoff if available.  (Problem and draft
296    patch reported by Dag-Erling Smørgrav.)
297
298  Changes to build procedure
299
300    The leap-seconds.list file is now copied from the IERS instead of
301    from its downstream counterpart at NIST, as the IERS version is
302    now in the public domain too and tends to be more up-to-date.
303    (Thanks to Martin Burnicki for liaisoning with the IERS.)
304
305  Changes to documentation
306
307    The strftime man page documents which struct tm members affect
308    which conversion specs, and that tzset is called.  (Problems
309    reported by Robert Elz and Steve Summit.)
310
311
312Release 2023d - 2023-12-21 20:02:24 -0800
313
314  Briefly:
315    Ittoqqortoormiit, Greenland changes time zones on 2024-03-31.
316    Vostok, Antarctica changed time zones on 2023-12-18.
317    Casey, Antarctica changed time zones five times since 2020.
318    Code and data fixes for Palestine timestamps starting in 2072.
319    A new data file zonenow.tab for timestamps starting now.
320
321  Changes to future timestamps
322
323    Ittoqqortoormiit, Greenland (America/Scoresbysund) joins most of
324    the rest of Greenland's timekeeping practice on 2024-03-31, by
325    changing its time zone from -01/+00 to -02/-01 at the same moment
326    as the spring-forward transition.  Its clocks will therefore not
327    spring forward as previously scheduled.  The time zone change
328    reverts to its common practice before 1981.  (Thanks to Jule Dabars.)
329
330    Fix predictions for DST transitions in Palestine in 2072-2075,
331    correcting a typo introduced in 2023a.  (Thanks to Jule Dabars.)
332
333  Changes to past and future timestamps
334
335    Vostok, Antarctica changed to +05 on 2023-12-18.  It had been at
336    +07 (not +06) for years.  (Thanks to Zakhary V. Akulov.)
337
338    Change data for Casey, Antarctica to agree with timeanddate.com,
339    by adding five time zone changes since 2020.  Casey is now at +08
340    instead of +11.
341
342  Changes to past tm_isdst flags
343
344    Much of Greenland, represented by America/Nuuk, changed its
345    standard time from -03 to -02 on 2023-03-25, not on 2023-10-28.
346    This does not affect UTC offsets, only the tm_isdst flag.
347    (Thanks to Thomas M. Steenholdt.)
348
349  New data file
350
351    A new data file zonenow.tab helps configure applications that use
352    timestamps dated from now on.  This simplifies configuration,
353    since users choose from a smaller Zone set.  The file's format is
354    experimental and subject to change.
355
356  Changes to code
357
358    localtime.c no longer mishandles TZif files that contain a single
359    transition into a DST regime.  Previously, it incorrectly assumed
360    DST was in effect before the transition too.  (Thanks to Alois
361    Treindl for debugging help.)
362
363    localtime.c's timeoff no longer collides with OpenBSD 7.4.
364
365    The C code now uses _Generic only if __STDC_VERSION__ says the
366    compiler is C11 or later.
367
368    tzselect now optionally reads zonenow.tab, to simplify when
369    configuring only for timestamps dated from now on.
370
371    tzselect no longer creates temporary files.
372
373    tzselect no longer mishandles the following:
374
375      Spaces and most other special characters in BUGEMAIL, PACKAGE,
376      TZDIR, and VERSION.
377
378      TZ strings when using mawk 1.4.3, which mishandles regular
379      expressions of the form /X{2,}/.
380
381      ISO 6709 coordinates when using an awk that lacks the GNU
382      extension of newlines in -v option-arguments.
383
384      Non UTF-8 locales when using an iconv command that lacks the GNU
385      //TRANSLIT extension.
386
387    zic no longer mishandles data for Palestine after the year 2075.
388    Previously, it incorrectly omitted post-2075 transitions that are
389    predicted for just before and just after Ramadan.  (Thanks to Ken
390    Murchison for debugging help.)
391
392    zic now works again on Linux 2.6.16 and 2.6.17 (2006).
393    (Problem reported by Rune Torgersen.)
394
395  Changes to build procedure
396
397    The Makefile is now more compatible with POSIX:
398     * It no longer defines AR, CC, CFLAGS, LDFLAGS, and SHELL.
399     * It no longer uses its own 'cc' in place of CC.
400     * It now uses ARFLAGS, with default specified by POSIX.
401     * It does not use LFLAGS incompatibly with POSIX.
402     * It uses the special .POSIX target.
403     * It quotes special characters more carefully.
404     * It no longer mishandles builds in an ISO 8859 locale.
405    Due to the CC changes, TZDIR is now #defined in a file tzdir.h
406    built by 'make', not in a $(CC) -D option.  Also, TZDEFAULT is
407    now treated like TZDIR as they have similar roles.
408
409  Changes to commentary
410
411     Limitations and hazards of the optional support for obsolescent
412     C89 platforms are documented better, along with a tentative
413     schedule for removing this support.
414
415
416Release 2023c - 2023-03-28 12:42:14 -0700
417
418  Changes to past and future timestamps
419
420    Model Lebanon's DST chaos by reverting data to tzdb 2023a.
421    (Thanks to Rany Hany for the heads-up.)
422
423
424Release 2023b - 2023-03-23 19:50:38 -0700
425
426  Changes to future timestamps
427
428    This year Lebanon springs forward April 20/21 not March 25/26.
429    (Thanks to Saadallah Itani.)  [This was reverted in 2023c.]
430
431
432Release 2023a - 2023-03-22 12:39:33 -0700
433
434  Briefly:
435    Egypt now uses DST again, from April through October.
436    This year Morocco springs forward April 23, not April 30.
437    Palestine delays the start of DST this year.
438    Much of Greenland still uses DST from 2024 on.
439    America/Yellowknife now links to America/Edmonton.
440    tzselect can now use current time to help infer timezone.
441    The code now defaults to C99 or later.
442    Fix use of C23 attributes.
443
444  Changes to future timestamps
445
446    Starting in 2023, Egypt will observe DST from April's last Friday
447    through October's last Thursday.  (Thanks to Ahmad ElDardiry.)
448    Assume the transition times are 00:00 and 24:00, respectively.
449
450    In 2023 Morocco's spring-forward transition after Ramadan
451    will occur April 23, not April 30.  (Thanks to Milamber.)
452    Adjust predictions for future years accordingly.  This affects
453    predictions for 2023, 2031, 2038, and later years.
454
455    This year Palestine will delay its spring forward from
456    March 25 to April 29 due to Ramadan.  (Thanks to Heba Hamad.)
457    Make guesses for future Ramadans too.
458
459    Much of Greenland, represented by America/Nuuk, will continue to
460    observe DST using European Union rules.  When combined with
461    Greenland's decision not to change the clocks in fall 2023,
462    America/Nuuk therefore changes from -03/-02 to -02/-01 effective
463    2023-10-29 at 01:00 UTC.  (Thanks to Thomas M. Steenholdt.)
464    This change from 2022g doesn't affect timestamps until 2024-03-30,
465    and doesn't affect tm_isdst until 2023-03-25.
466
467  Changes to past timestamps
468
469    America/Yellowknife has changed from a Zone to a backward
470    compatibility Link, as it no longer differs from America/Edmonton
471    since 1970.  (Thanks to Almaz Mingaleev.)  This affects some
472    pre-1948 timestamps.  The old data are now in 'backzone'.
473
474  Changes to past time zone abbreviations
475
476    When observing Moscow time, Europe/Kirov and Europe/Volgograd now
477    use the abbreviations MSK/MSD instead of numeric abbreviations,
478    for consistency with other timezones observing Moscow time.
479
480  Changes to code
481
482    You can now tell tzselect local time, to simplify later choices.
483    Select the 'time' option in its first prompt.
484
485    You can now compile with -DTZNAME_MAXIMUM=N to limit time zone
486    abbreviations to N bytes (default 255).  The reference runtime
487    library now rejects POSIX-style TZ strings that contain longer
488    abbreviations, treating them as UTC.  Previously the limit was
489    platform dependent and abbreviations were silently truncated to
490    16 bytes even when the limit was greater than 16.
491
492    The code by default is now designed for C99 or later.  To build on
493    a mostly-C89 platform, compile with -DPORT_TO_C89; this should
494    work on C89 platforms that also support C99 'long long' and
495    perhaps a few other extensions to C89.  To support C89 callers of
496    tzcode's library, compile with -DSUPPORT_C89; however, this could
497    trigger latent bugs in C99-or-later callers.  The two new macros
498    are transitional aids planned to be removed in a future version
499    (say, in 2029), when C99 or later will be required.
500
501    The code now builds again on pre-C99 platforms, if you compile
502    with -DPORT_TO_C89.  This fixes a bug introduced in 2022f.
503
504    On C23-compatible platforms tzcode no longer uses syntax like
505    'static [[noreturn]] void usage(void);'.  Instead, it uses
506    '[[noreturn]] static void usage(void);' as strict C23 requires.
507    (Problem reported by Houge Langley.)
508
509    The code's functions now constrain their arguments with the C
510    'restrict' keyword consistently with their documentation.
511    This may allow future optimizations.
512
513    zdump again builds standalone with ckdadd and without setenv,
514    fixing a bug introduced in 2022g.  (Problem reported by panic.)
515
516    leapseconds.awk can now process a leap seconds file that never
517    expires; this might be useful if leap seconds are discontinued.
518
519  Changes to commentary
520
521    tz-link.html has a new section "Coordinating with governments and
522    distributors".  (Thanks to Neil Fuller for some of the text.)
523
524    To improve tzselect diagnostics, zone1970.tab's comments column is
525    now limited to countries that have multiple timezones.
526
527    Note that there are plans to discontinue leap seconds by 2035.
528
529
530Release 2022g - 2022-11-29 08:58:31 -0800
531
532  Briefly:
533    The northern edge of Chihuahua changes to US timekeeping.
534    Much of Greenland stops changing clocks after March 2023.
535    Fix some pre-1996 timestamps in northern Canada.
536    C89 is now deprecated; please use C99 or later.
537    Portability fixes for AIX, libintl, MS-Windows, musl, z/OS
538    In C code, use more C23 features if available.
539    C23 timegm now supported by default
540    Fixes for unlikely integer overflows
541
542  Changes to future timestamps
543
544    In the Mexican state of Chihuahua, the border strip near the US
545    will change to agree with nearby US locations on 2022-11-30.
546    The strip's western part, represented by Ciudad Juárez, switches
547    from -06 all year to -07/-06 with US DST rules, like El Paso, TX.
548    The eastern part, represented by Ojinaga, will observe US DST next
549    year, like Presidio, TX.  (Thanks to Heitor David Pinto.)
550    A new Zone America/Ciudad_Juarez splits from America/Ojinaga.
551
552    Much of Greenland, represented by America/Nuuk, stops observing
553    winter time after March 2023, so its daylight saving time becomes
554    standard time.  (Thanks to Jonas Nyrup and Jürgen Appel.)
555
556  Changes to past timestamps
557
558    Changes for pre-1996 northern Canada (thanks to Chris Walton):
559
560      Merge America/Iqaluit and America/Pangnirtung into the former,
561      with a backward compatibility link for the latter name.
562      There is no good evidence the two locations differ since 1970.
563      This change affects pre-1996 America/Pangnirtung timestamps.
564
565      Cambridge Bay, Inuvik, Iqaluit, Rankin Inlet, Resolute and
566      Yellowknife did not observe DST in 1965, and did observe DST
567      from 1972 through 1979.
568
569      Whitehorse moved from -09 to -08 on 1966-02-27, not 1967-05-28.
570
571    Colombia's 1993 fallback was 02-06 24:00, not 04-04 00:00.
572    (Thanks to Alois Treindl.)
573
574    Singapore's 1981-12-31 change was at 16:00 UTC (23:30 local time),
575    not 24:00 local time.  (Thanks to Geoff Clare via Robert Elz.)
576
577  Changes to code
578
579    Although tzcode still works with C89, bugs found in recent routine
580    maintenance indicate that bitrot has set in and that in practice
581    C89 is no longer used to build tzcode.  As it is a maintenance
582    burden, support for C89 is planned to be removed soon.  Instead,
583    please use compilers compatible with C99, C11, C17, or C23.
584
585    timegm, which tzcode implemented in 1989, will finally be
586    standardized 34 years later as part of C23, so timegm is now
587    supported even if STD_INSPIRED is not defined.
588
589    Fix bug in zdump's tzalloc emulation on hosts that lack tm_zone.
590    (Problem reported by Đoàn Trần Công Danh.)
591
592    Fix bug in zic on hosts where malloc(0) yields NULL on success.
593    (Problem reported by Tim McBrayer for AIX 6.1.)
594
595    Fix zic configuration to avoid linkage failures on some platforms.
596    (Problems reported by Gilmore Davidson and Igor Ivanov.)
597
598    Work around MS-Windows nmake incompatibility with POSIX.
599    (Problem reported by Manuela Friedrich.)
600
601    Port mktime and strftime to debugging platforms where accessing
602    uninitialized data has undefined behavior (strftime problem
603    reported by Robert Elz).
604
605    Check more carefully for unlikely integer overflows, preferring
606    C23 <stdckdint.h> to overflow checking by hand, as the latter has
607    had obscure bugs.
608
609  Changes to build procedure
610
611    New Makefile rule check_mild that skips checking whether Link
612    lines are in the file 'backward'.  (Inspired by a suggestion from
613    Stephen Colebourne.)
614
615
616Release 2022f - 2022-10-28 18:04:57 -0700
617
618  Briefly:
619    Mexico will no longer observe DST except near the US border.
620    Chihuahua moves to year-round -06 on 2022-10-30.
621    Fiji no longer observes DST.
622    Move links to 'backward'.
623    In vanguard form, GMT is now a Zone and Etc/GMT a link.
624    zic now supports links to links, and vanguard form uses this.
625    Simplify four Ontario zones.
626    Fix a Y2438 bug when reading TZif data.
627    Enable 64-bit time_t on 32-bit glibc platforms.
628    Omit large-file support when no longer needed.
629    In C code, use some C23 features if available.
630    Remove no-longer-needed workaround for Qt bug 53071.
631
632  Changes to future timestamps
633
634    Mexico will no longer observe DST after 2022, except for areas
635    near the US border that continue to observe US DST rules.
636    On 2022-10-30 at 02:00 the Mexican state of Chihuahua moves
637    from -07 (-06 with DST) to year-round -06, thus not changing
638    its clocks that day.  The new law states that Chihuahua
639    near the US border no longer observes US DST.
640    (Thanks to gera for the heads-up about Chihuahua.)
641
642    Fiji will not observe DST in 2022/3.  (Thanks to Shalvin Narayan.)
643    For now, assume DST is suspended indefinitely.
644
645  Changes to data
646
647    Move links to 'backward' to ease and simplify link maintenance.
648    This affects generated data only if you use 'make BACKWARD='.
649
650    GMT is now a Zone and Etc/GMT a link instead of vice versa,
651    as GMT is needed for leap second support whereas Etc/GMT is not.
652    However, this change exposes a bug in TZUpdater 2.3.2 so it is
653    present only in vanguard form for now.
654
655    Vanguard form now uses links to links, as zic now supports this.
656
657  Changes to past timestamps
658
659    Simplify four Ontario zones, as most of the post-1970 differences
660    seem to have been imaginary.  (Problem reported by Chris Walton.)
661    Move America/Nipigon, America/Rainy_River, and America/Thunder_Bay
662    to 'backzone'; backward-compatibility links still work, albeit
663    with some different timestamps before November 2005.
664
665  Changes to code
666
667    zic now supports links to links regardless of input line order.
668    For example, if Australia/Sydney is a Zone, the lines
669      Link Australia/Canberra Australia/ACT
670      Link Australia/Sydney Australia/Canberra
671    now work correctly, even though the shell commands
672      ln Australia/Canberra Australia/ACT
673      ln Australia/Sydney Australia/Canberra
674    would fail because the first command attempts to use a link
675    Australia/Canberra that does not exist until after the second
676    command is executed.  Previously, zic had unspecified behavior if
677    a Link line's target was another link, and zic often misbehaved if
678    a Link line's target was a later Link line.
679
680    Fix line number in zic's diagnostic for a link to a link.
681
682    Fix a bug that caused localtime to mishandle timestamps starting
683    in the year 2438 when reading data generated by 'zic -b fat' when
684    distant-future DST transitions occur at times given in standard
685    time or in UT, not the usual case of local time.  This occurs when
686    the corresponding .zi Rule lines specify DST transitions with TO
687    columns of 'max' and AT columns that end in 's' or 'u'.  The
688    number 2438 comes from the 32-bit limit in the year 2038, plus the
689    400-year Gregorian cycle.  (Problem reported by Bradley White.)
690
691    On glibc 2.34 and later, which optionally supports 64-bit time_t
692    on platforms like x86 where time_t was traditionally 32 bits,
693    default time_t to 64 instead of 32 bits.  This lets functions like
694    localtime support timestamps after the year 2038, and fixes
695    year-2038 problems in zic when accessing files dated after 2038.
696    To continue to limit time_t to 32 bits on these platforms, use
697    "make CFLAGS='-D_TIME_BITS=32'".
698
699    In C code, do not enable large-file support on platforms like AIX
700    and macOS that no longer need it now that tzcode does not use
701    off_t or related functions like 'stat'.  Large-file support is
702    still enabled by default on GNU/Linux, as it is needed for 64-bit
703    time_t support.
704
705    In C code, prefer C23 keywords to pre-C23 macros for alignof,
706    bool, false, and true.  Also, use the following C23 features if
707    available: __has_include, unreachable.
708
709    zic no longer works around Qt bug 53071, as the relevant Qt
710    releases have been out of support since 2019.  This change affects
711    only fat TZif files, as thin files never had the workaround.
712
713    zdump no longer modifies the environ vector when compiled on
714    platforms lacking tm_zone or when compiled with -DUSE_LTZ=0.
715    This avoid undefined behavior on POSIX platforms.
716
717
718Release 2022e - 2022-10-11 11:13:02 -0700
719
720  Briefly:
721    Jordan and Syria switch from +02/+03 with DST to year-round +03.
722
723  Changes to future timestamps
724
725    Jordan and Syria are abandoning the DST regime and are changing to
726    permanent +03, so they will not fall back from +03 to +02 on
727    2022-10-28.  (Thanks to Steffen Thorsen and Issam Al-Zuwairi.)
728
729  Changes to past timestamps
730
731    On 1922-01-01 Tijuana adopted standard time at 00:00, not 01:00.
732
733  Changes to past time zone abbreviations and DST flags
734
735    The temporary advancement of clocks in central Mexico in summer
736    1931 is now treated as daylight saving time, instead of as two
737    changes to standard time.
738
739
740Release 2022d - 2022-09-23 12:02:57 -0700
741
742  Briefly:
743    Palestine transitions are now Saturdays at 02:00.
744    Simplify three Ukraine zones into one.
745
746  Changes to future timestamps
747
748    Palestine now springs forward and falls back at 02:00 on the
749    first Saturday on or after March 24 and October 24, respectively.
750    This means 2022 falls back 10-29 at 02:00, not 10-28 at 01:00.
751    (Thanks to Heba Hamad.)
752
753  Changes to past timestamps
754
755    Simplify three Ukraine zones to one, since the post-1970
756    differences seem to have been imaginary.  Move Europe/Uzhgorod and
757    Europe/Zaporozhye to 'backzone'; backward-compatibility links
758    still work, albeit with different timestamps before October 1991.
759
760
761Release 2022c - 2022-08-15 17:47:18 -0700
762
763  Briefly:
764    Work around awk bug in FreeBSD, macOS, etc.
765    Improve tzselect on intercontinental Zones.
766
767  Changes to code
768
769    Work around a bug in onetrueawk that broke commands like
770    'make traditional_tarballs' on FreeBSD, macOS, etc.
771    (Problem reported by Deborah Goldsmith.)
772
773    Add code to tzselect that uses experimental structured comments in
774    zone1970.tab to clarify whether Zones like Africa/Abidjan and
775    Europe/Istanbul cross continent or ocean boundaries.
776    (Inspired by a problem reported by Peter Krefting.)
777
778    Fix bug with 'zic -d /a/b/c' when /a is unwritable but the
779    directory /a/b already exists.
780
781    Remove zoneinfo2tdf.pl, as it was unused and triggered false
782    malware alarms on some email servers.
783
784
785Release 2022b - 2022-08-10 15:38:32 -0700
786
787  Briefly:
788    Chile's DST is delayed by a week in September 2022.
789    Iran no longer observes DST after 2022.
790    Rename Europe/Kiev to Europe/Kyiv.
791    New zic -R option
792    Vanguard form now uses %z.
793    Finish moving duplicate-since-1970 zones to 'backzone'.
794    New build option PACKRATLIST
795    New tailored_tarballs target, replacing rearguard_tarballs
796
797  Changes to future timestamps
798
799    Chile's 2022 DST start is delayed from September 4 to September 11.
800    (Thanks to Juan Correa.)
801
802    Iran plans to stop observing DST permanently, after it falls back
803    on 2022-09-21.  (Thanks to Ali Mirjamali.)
804
805  Changes to past timestamps
806
807    Finish moving to 'backzone' the location-based zones whose
808    timestamps since 1970 are duplicates; adjust links accordingly.
809    This change ordinarily affects only pre-1970 timestamps, and with
810    the new PACKRATLIST option it does not affect any timestamps.
811    In this round the affected zones are Antarctica/Vostok,
812    Asia/Brunei, Asia/Kuala_Lumpur, Atlantic/Reykjavik,
813    Europe/Amsterdam, Europe/Copenhagen, Europe/Luxembourg,
814    Europe/Monaco, Europe/Oslo, Europe/Stockholm, Indian/Christmas,
815    Indian/Cocos, Indian/Kerguelen, Indian/Mahe, Indian/Reunion,
816    Pacific/Chuuk, Pacific/Funafuti, Pacific/Majuro, Pacific/Pohnpei,
817    Pacific/Wake and Pacific/Wallis, and the affected links are
818    Arctic/Longyearbyen, Atlantic/Jan_Mayen, Iceland, Pacific/Ponape,
819    Pacific/Truk, and Pacific/Yap.
820
821    From fall 1994 through fall 1995, Shanks wrote that Crimea's
822    DST transitions were at 02:00 standard time, not at 00:00.
823    (Thanks to Michael Deckers.)
824
825    Iran adopted standard time in 1935, not 1946.  In 1977 it observed
826    DST from 03-21 23:00 to 10-20 24:00; its 1978 transitions were on
827    03-24 and 08-05, not 03-20 and 10-20; and its spring 1979
828    transition was on 05-27, not 03-21.
829    (Thanks to Roozbeh Pournader and Francis Santoni.)
830
831    Chile's observance of -04 from 1946-08-29 through 1947-03-31 was
832    considered DST, not standard time.  Santiago and environs had moved
833    their clocks back to rejoin the rest of mainland Chile; put this
834    change at the end of 1946-08-28.  (Thanks to Michael Deckers.)
835
836    Some old, small clock transitions have been removed, as people at
837    the time did not change their clocks.  This affects Asia/Hong_Kong
838    in 1904, Asia/Ho_Chi_Minh in 1906, and Europe/Dublin in 1880.
839
840  Changes to zone name
841
842    Rename Europe/Kiev to Europe/Kyiv, as "Kyiv" is more common in
843    English now.  Spelling of other names in Ukraine has not yet
844    demonstrably changed in common English practice so for now these
845    names retain old spellings, as in other countries (e.g.,
846    Europe/Prague not "Praha", and Europe/Sofia not "Sofiya").
847
848  Changes to code
849
850    zic has a new option '-R @N' to output explicit transitions < N.
851    (Need suggested by Almaz Mingaleev.)
852
853    'zic -r @N' no longer outputs bad data when N < first transition.
854    (Problem introduced in 2021d and reported by Peter Krefting.)
855
856    zic now checks its input for NUL bytes and unterminated lines, and
857    now supports input line lengths up to 2048 (not 512) bytes.
858
859    gmtime and related code now use the abbreviation "UTC" not "GMT".
860    POSIX is being revised to require this.
861
862    When tzset and related functions set vestigial static variables
863    like tzname, they now prefer specified timestamps to unspecified ones.
864    (Problem reported by Almaz Mingaleev.)
865
866    zic no longer complains "can't determine time zone abbreviation to
867    use just after until time" when a transition to a new standard
868    time occurs simultaneously with the first DST fallback transition.
869
870  Changes to build procedure
871
872    Source data in vanguard form now uses the %z notation, introduced
873    in release 2015f.  For example, for America/Sao_Paulo vanguard
874    form contains the zone continuation line "-3:00 Brazil %z", which
875    is simpler and more reliable than the line "-3:00 Brazil -03/-02"
876    used in main and rearguard forms.  The plan is for the main form
877    to use %z eventually; in the meantime maintainers of zi parsers
878    are encouraged to test the parsers on vanguard.zi.
879
880    The Makefile has a new PACKRATLIST option to select a subset of
881    'backzone'.  For example, 'make PACKRATDATA=backzone
882    PACKRATLIST=zone.tab' now generates TZif files identical to those
883    of the global-tz project.
884
885    The Makefile has a new tailored_tarballs target for generating
886    special-purpose tarballs.  It generalizes and replaces the
887    rearguard_tarballs target and related targets and macros, which
888    are now obsolescent.
889
890    'make install' now defaults LOCALTIME to Factory not GMT,
891    which means the default abbreviation is now "-00" not "GMT".
892
893    Remove the posix_packrat target, marked obsolescent in 2016a.
894
895
896Release 2022a - 2022-03-15 23:02:01 -0700
897
898  Briefly:
899    Palestine will spring forward on 2022-03-27, not -03-26.
900    zdump -v now outputs better failure indications.
901    Bug fixes for code that reads corrupted TZif data.
902
903  Changes to future timestamps
904
905    Palestine will spring forward on 2022-03-27, not 2022-03-26.
906    (Thanks to Heba Hamad.)  Predict future transitions for first
907    Sunday >= March 25.  Additionally, predict fallbacks to be the first
908    Friday on or after October 23, not October's last Friday, to be more
909    consistent with recent practice.  The first differing fallback
910    prediction is on 2025-10-24, not 2025-10-31.
911
912  Changes to past timestamps
913
914    From 1992 through spring 1996, Ukraine's DST transitions were at
915    02:00 standard time, not at 01:00 UTC.  (Thanks to Alois Treindl.)
916
917    Chile's Santiago Mean Time and its LMT precursor have been adjusted
918    eastward by 1 second to align with past and present law.
919
920  Changes to commentary
921
922    Add several references for Chile's 1946/1947 transitions, some of
923    which only affected portions of the country.
924
925  Changes to code
926
927    Fix bug when mktime gets confused by truncated TZif files with
928    unspecified local time.  (Problem reported by Almaz Mingaleev.)
929
930    Fix bug when 32-bit time_t code reads malformed 64-bit TZif data.
931    (Problem reported by Christos Zoulas.)
932
933    When reading a version 2 or later TZif file, the TZif reader now
934    validates the version 1 header and data block only enough to skip
935    over them, as recommended by RFC 8536 section 4.  Also, the TZif
936    reader no longer mistakenly attempts to parse a version 1 TZIf
937    file header as a TZ string.
938
939    zdump -v now outputs "(localtime failed)" and "(gmtime failed)"
940    when local time and UT cannot be determined for a timestamp.
941
942  Changes to build procedure
943
944    Distribution tarballs now use standard POSIX.1-1988 ustar format
945    instead of GNU format.  Although the formats are almost identical
946    for these tarballs, ustar headers' magic fields contain "ustar"
947    instead of "ustar ", and their version fields contain "00" instead
948    of " ".  The two formats are planned to diverge more significantly
949    for tzdb releases after 2242-03-16 12:56:31 UTC, when the ustar
950    format becomes obsolete and the tarballs switch to pax format, an
951    extension of ustar.  For details about these formats, please see
952    "pax - portable archive interchange", IEEE Std 1003.1-2017,
953    <https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13>.
954
955
956Release 2021e - 2021-10-21 18:41:00 -0700
957
958  Changes to future timestamps
959
960    Palestine will fall back 10-29 (not 10-30) at 01:00.
961    (Thanks to P Chan and Heba Hemad.)
962
963
964Release 2021d - 2021-10-15 13:48:18 -0700
965
966  Briefly:
967    Fiji suspends DST for the 2021/2022 season.
968    'zic -r' marks unspecified timestamps with "-00".
969
970  Changes to future timestamps
971
972    Fiji will suspend observance of DST for the 2021/2022 season.
973    Assume for now that it will return next year.  (Thanks to Jashneel
974    Kumar and P Chan.)
975
976  Changes to code
977
978    'zic -r' now uses "-00" time zone abbreviations for intervals
979    with UT offsets that are unspecified due to -r truncation.
980    This implements a change in draft Internet RFC 8536bis.
981
982
983Release 2021c - 2021-10-01 14:21:49 -0700
984
985  Briefly:
986    Revert most 2021b changes to 'backward'.
987    Fix 'zic -b fat' bug in pre-1970 32-bit data.
988    Fix two Link line typos.
989    Distribute SECURITY file.
990
991    This release is intended as a bugfix release, to fix compatibility
992    problems and typos reported since 2021b was released.
993
994  Changes to Link directives
995
996    Revert almost all of 2021b's changes to the 'backward' file,
997    by moving Link directives back to where they were in 2021a.
998    Although 'zic' doesn't care which source file contains a Link
999    directive, some downstream uses ran into trouble with the move.
1000    (Problem reported by Stephen Colebourne for Joda-Time.)
1001
1002    Fix typo that linked Atlantic/Jan_Mayen to the wrong location
1003    (problem reported by Chris Walton).
1004
1005    Fix 'backzone' typo that linked America/Virgin to the wrong
1006    location (problem reported by Michael Deckers).
1007
1008  Changes to code
1009
1010    Fix a bug in 'zic -b fat' that caused old timestamps to be
1011    mishandled in 32-bit-only readers (problem reported by Daniel
1012    Fischer).
1013
1014  Changes to documentation
1015
1016    Distribute the SECURITY file (problem reported by Andreas Radke).
1017
1018
1019Release 2021b - 2021-09-24 16:23:00 -0700
1020
1021  Briefly:
1022    Jordan now starts DST on February's last Thursday.
1023    Samoa no longer observes DST.
1024    Merge more location-based Zones whose timestamps agree since 1970.
1025    Move some backward-compatibility links to 'backward'.
1026    Rename Pacific/Enderbury to Pacific/Kanton.
1027    Correct many pre-1993 transitions in Malawi, Portugal, etc.
1028    zic now creates each output file or link atomically.
1029    zic -L no longer omits the POSIX TZ string in its output.
1030    zic fixes for truncation and leap second table expiration.
1031    zic now follows POSIX for TZ strings using all-year DST.
1032    Fix some localtime crashes and bugs in obscure cases.
1033    zdump -v now outputs more-useful boundary cases.
1034    tzfile.5 better matches a draft successor to RFC 8536.
1035    A new file SECURITY.
1036
1037    This release is prompted by recent announcements by Jordan and Samoa.
1038    It incorporates many other changes that had accumulated since 2021a.
1039    However, it omits most proposed changes that merged all Zones
1040    agreeing since 1970, as concerns were raised about doing too many of
1041    these changes at once.  It does keeps some of these changes in the
1042    interest of making tzdb more equitable one step at a time; see
1043    "Merge more location-based Zones" below.
1044
1045  Changes to future timestamps
1046
1047    Jordan now starts DST on February's last Thursday.
1048    (Thanks to Steffen Thorsen.)
1049
1050    Samoa no longer observes DST.  (Thanks to Geoffrey D. Bennett.)
1051
1052  Changes to zone name
1053
1054    Rename Pacific/Enderbury to Pacific/Kanton.  When we added
1055    Enderbury in 1993, we did not know that it is uninhabited and that
1056    Kanton (population two dozen) is the only inhabited location in
1057    that timezone.  The old name is now a backward-compatibility link.
1058
1059  Changes to past timestamps
1060
1061    Correct many pre-1993 transitions, fixing entries originally
1062    derived from Shanks, Whitman, and Mundell.  The fixes include:
1063      - Barbados: standard time was introduced in 1911, not 1932; and
1064	DST was observed in 1942-1944
1065      - Cook Islands: In 1899 they switched from east to west of GMT,
1066	celebrating Christmas for two days.  They (and Niue) switched
1067	to standard time in 1952, not 1901.
1068      - Guyana: corrected LMT for Georgetown; the introduction of
1069	standard time in 1911, not 1915; and corrections to 1975 and
1070	1992 transitions
1071      - Kanton: uninhabited before 1937-08-31
1072      - Niue: only observed -11:20 from 1952 through 1964, then went to
1073        -11 instead of -11:30
1074      - Portugal: DST was observed in 1950
1075      - Tonga: corrected LMT; the introduction of standard time in 1945,
1076        not 1901; and corrections to the transition from +12:20 to +13
1077        in 1961, not 1941
1078    Additional fixes to entries in the 'backzone' file include:
1079      - Enderbury: inhabited only 1860/1885 and 1938-03-06/1942-02-09
1080      - The Gambia: 1933 and 1942 transitions
1081      - Malawi: several 1911 through 1925 transitions
1082      - Sierra Leone: several 1913 through 1941 transitions, and DST
1083	was NOT observed in 1957 through 1962
1084    (Thanks to P Chan, Michael Deckers, Alexander Krivenyshev and
1085    Alois Treindl.)
1086
1087    Merge more location-based Zones whose timestamps agree since 1970,
1088    as pre-1970 timestamps are out of scope.  This is part of a
1089    process that has been ongoing since 2013.  This does not affect
1090    post-1970 timestamps, and timezone historians who build with 'make
1091    PACKRATDATA=backzone' should see no changes to pre-1970 timestamps.
1092    When merging, keep the most-populous location's data, and move
1093    data for other locations to 'backzone' with a backward
1094    link in 'backward'.  For example, move America/Creston data to
1095    'backzone' with a link in 'backward' from America/Phoenix because
1096    the two timezones' timestamps agree since 1970; this change
1097    affects some pre-1968 timestamps in America/Creston because
1098    Creston and Phoenix disagreed before 1968.  The affected Zones
1099    are Africa/Accra, America/Atikokan, America/Blanc-Sablon,
1100    America/Creston, America/Curacao, America/Nassau,
1101    America/Port_of_Spain, Antarctica/DumontDUrville, and
1102    Antarctica/Syowa.
1103
1104  Changes to maintenance procedure
1105
1106    The new file SECURITY covers how to report security-related bugs.
1107
1108    Several backward-compatibility links have been moved to the
1109    'backward' file.  These links, which range from Africa/Addis_Ababa
1110    to Pacific/Saipan, are only for compatibility with now-obsolete
1111    guidelines suggesting an entry for every ISO 3166 code.
1112    The intercontinental convenience links Asia/Istanbul and
1113    Europe/Nicosia have also been moved to 'backward'.
1114
1115  Changes to code
1116
1117    zic now creates each output file or link atomically,
1118    possibly by creating a temporary file and then renaming it.
1119    This avoids races where a TZ setting would temporarily stop
1120    working while zic was installing a replacement file or link.
1121
1122    zic -L no longer omits the POSIX TZ string in its output.
1123    Starting with 2020a, zic -L truncated its output according to the
1124    "Expires" directive or "#expires" comment in the leapseconds file.
1125    The resulting TZif files omitted daylight saving transitions after
1126    the leap second table expired, which led to far less accurate
1127    predictions of times after the expiry.  Although future timestamps
1128    cannot be converted accurately in the presence of leap seconds, it
1129    is more accurate to convert near-future timestamps with a few
1130    seconds error than with an hour error, so zic -L no longer
1131    truncates output in this way.
1132
1133    Instead, when zic -L is given the "Expires" directive, it now
1134    outputs the expiration by appending a no-change entry to the leap
1135    second table.  Although this should work well with most TZif
1136    readers, it does not conform to Internet RFC 8536 and some pickier
1137    clients (including tzdb 2017c through 2021a) reject it, so
1138    "Expires" directives are currently disabled by default.  To enable
1139    them, set the EXPIRES_LINE Makefile variable.  If a TZif file uses
1140    this new feature it is marked with a new TZif version number 4,
1141    a format intended to be documented in a successor to RFC 8536.
1142    The old-format "#expires" comments are now treated solely as
1143    comments and have no effect on the TZif files.
1144
1145    zic -L LEAPFILE -r @LO no longer generates an invalid TZif file
1146    that omits leap second information for the range LO..B when LO
1147    falls between two leap seconds A and B.  Instead, it generates a
1148    TZif version 4 file that represents the previously missing
1149    information.
1150
1151    The TZif reader now allows the leap second table to begin with a
1152    correction other than -1 or +1, and to contain adjacent
1153    transitions with equal corrections.  This supports TZif version 4.
1154
1155    The TZif reader now lets leap seconds occur less than 28 days
1156    apart.  This supports possible future TZif extensions.
1157
1158    Fix bug that caused 'localtime' etc. to crash when TZ was
1159    set to a all-year DST string like "EST5EDT4,0/0,J365/25" that does
1160    not conform to POSIX but does conform to Internet RFC 8536.
1161
1162    Fix another bug that caused 'localtime' etc. to crash when TZ was
1163    set to a POSIX-conforming but unusual TZ string like
1164    "EST5EDT4,0/0,J365/0", where almost all the year is DST.
1165
1166    Fix yet another bug that caused 'localtime' etc. to mishandle slim
1167    TZif files containing leap seconds after the last explicit
1168    transition in the table, or when handling far-future timestamps
1169    in slim TZif files lacking leap seconds.
1170
1171    Fix localtime misbehavior involving positive leap seconds.
1172    This change affects only behavior for "right" system time,
1173    which contains leap seconds, and only if the UT offset is
1174    not a multiple of 60 seconds when a positive leap second occurs.
1175    (No such timezone exists in tzdb, luckily.)  Without the fix,
1176    the timestamp was ambiguous during a positive leap second.
1177    With the fix, any seconds occurring after a positive leap second
1178    and within the same localtime minute are counted through 60, not
1179    through 59; their UT offset (tm_gmtoff) is the same as before.
1180    Here is how the fix affects timestamps in a timezone with UT
1181    offset +01:23:45 (5025 seconds) and with a positive leap second at
1182    1972-06-30 23:59:60 UTC (78796800):
1183
1184	time_t    without the fix      with the fix
1185	78796800  1972-07-01 01:23:45  1972-07-01 01:23:45 (leap second)
1186	78796801  1972-07-01 01:23:45  1972-07-01 01:23:46
1187	...
1188	78796815  1972-07-01 01:23:59  1972-07-01 01:23:60
1189	78796816  1972-07-01 01:24:00  1972-07-01 01:24:00
1190
1191    Fix an unlikely bug that caused 'localtime' etc. to misbehave if
1192    civil time changes a few seconds before time_t wraps around, when
1193    leap seconds are enabled.
1194
1195    Fix bug in zic -r; in some cases, the dummy time type after the
1196    last time transition disagreed with the TZ string, contrary to
1197    Internet RFC 8563 section 3.3.
1198
1199    Fix a bug with 'zic -r @X' when X is a negative leap second that
1200    has a nonnegative correction.  Without the fix, the output file
1201    was truncated so that X appeared to be a positive leap second.
1202    Fix a similar, even less likely bug when truncating at a positive
1203    leap second that has a nonpositive correction.
1204
1205    zic -r now reports an error if given rolling leap seconds, as this
1206    usage has never generally worked and is evidently unused.
1207
1208    zic now generates a POSIX-conforming TZ string for TZif files
1209    where all-year DST is predicted for the indefinite future.
1210    For example, for all-year Eastern Daylight Time, zic now generates
1211    "XXX3EDT4,0/0,J365/23" where it previously generated
1212    "EST5EDT,0/0,J365/25" or "".  (Thanks to Michael Deckers for
1213    noting the possibility of POSIX conformance.)
1214
1215    zic.c no longer requires sys/wait.h (thanks to spazmodius for
1216    noting it wasn't needed).
1217
1218    When reading slim TZif files, zdump no longer mishandles leap
1219    seconds on the rare platforms where time_t counts leap seconds,
1220    fixing a bug introduced in 2014g.
1221
1222    zdump -v now outputs timestamps at boundaries of what localtime
1223    and gmtime can represent, instead of the less useful timestamps
1224    one day after the minimum and one day before the maximum.
1225    (Thanks to Arthur David Olson for prototype code, and to Manuela
1226    Friedrich for debugging help.)
1227
1228    zdump's -c and -t options are now consistently inclusive for the
1229    lower time bound and exclusive for the upper.  Formerly they were
1230    inconsistent.  (Confusion noted by Martin Burnicki.)
1231
1232  Changes to build procedure
1233
1234    You can now compile with -DHAVE_MALLOC_ERRNO=0 to port to
1235    non-POSIX hosts where malloc doesn't set errno.
1236    (Problem reported by Jan Engelhardt.)
1237
1238  Changes to documentation
1239
1240    tzfile.5 better matches a draft successor to RFC 8536
1241    <https://datatracker.ietf.org/doc/draft-murchison-rfc8536bis/01/>.
1242
1243
1244Release 2021a - 2021-01-24 10:54:57 -0800
1245
1246  Changes to future timestamps
1247
1248    South Sudan changes from +03 to +02 on 2021-02-01 at 00:00.
1249    (Thanks to Steffen Thorsen.)
1250
1251
1252Release 2020f - 2020-12-29 00:17:46 -0800
1253
1254  Change to build procedure
1255
1256    'make rearguard_tarballs' no longer generates a bad rearguard.zi,
1257    fixing a 2020e bug.  (Problem reported by Deborah Goldsmith.)
1258
1259
1260Release 2020e - 2020-12-22 15:14:34 -0800
1261
1262  Briefly:
1263    Volgograd switches to Moscow time on 2020-12-27 at 02:00.
1264
1265  Changes to future timestamps
1266
1267    Volgograd changes time zone from +04 to +03 on 2020-12-27 at 02:00.
1268    (Thanks to Alexander Krivenyshev and Stepan Golosunov.)
1269
1270  Changes to past timestamps
1271
1272    Correct many pre-1986 transitions, fixing entries originally
1273    derived from Shanks.  The fixes include:
1274      - Australia: several 1917 through 1971 transitions
1275      - The Bahamas: several 1941 through 1945 transitions
1276      - Bermuda: several 1917 through 1956 transitions
1277      - Belize: several 1942 through 1968 transitions
1278      - Ghana: several 1915 through 1956 transitions
1279      - Israel and Palestine: several 1940 through 1985 transitions
1280      - Kenya and adjacent: several 1908 through 1960 transitions
1281      - Nigeria and adjacent: correcting LMT in Lagos, and several 1905
1282        through 1919 transitions
1283      - Seychelles: the introduction of standard time in 1907, not 1906
1284      - Vanuatu: DST in 1973-1974, and a corrected 1984 transition
1285    (Thanks to P Chan.)
1286
1287    Because of the Australia change, Australia/Currie (King Island) is
1288    no longer needed, as it is identical to Australia/Hobart for all
1289    timestamps since 1970 and was therefore created by mistake.
1290    Australia/Currie has been moved to the 'backward' file and its
1291    corrected data moved to the 'backzone' file.
1292
1293  Changes to past time zone abbreviations and DST flags
1294
1295    To better match legislation in Turks and Caicos, the 2015 shift to
1296    year-round observance of -04 is now modeled as AST throughout before
1297    returning to Eastern Time with US DST in 2018, rather than as
1298    maintaining EDT until 2015-11-01.  (Thanks to P Chan.)
1299
1300  Changes to documentation
1301
1302    The zic man page now documents zic's coalescing of transitions
1303    when a zone falls back just before DST springs forward.
1304
1305
1306Release 2020d - 2020-10-21 11:24:13 -0700
1307
1308  Briefly:
1309    Palestine ends DST earlier than predicted, on 2020-10-24.
1310
1311  Changes to past and future timestamps
1312
1313    Palestine ends DST on 2020-10-24 at 01:00, instead of 2020-10-31
1314    as previously predicted (thanks to Sharef Mustafa.)  Its
1315    2019-10-26 fall-back was at 00:00, not 01:00 (thanks to Steffen
1316    Thorsen.)  Its 2015-10-23 transition was at 01:00 not 00:00, and
1317    its spring 2020 transition was on March 28 at 00:00, not March 27
1318    (thanks to Pierre Cashon.)  This affects Asia/Gaza and
1319    Asia/Hebron.  Assume future spring and fall transitions will be on
1320    the Saturday preceding the last Sunday of March and October,
1321    respectively.
1322
1323
1324Release 2020c - 2020-10-16 11:15:53 -0700
1325
1326  Briefly:
1327    Fiji starts DST later than usual, on 2020-12-20.
1328
1329  Changes to future timestamps
1330
1331    Fiji will start DST on 2020-12-20, instead of 2020-11-08 as
1332    previously predicted.  DST will still end on 2021-01-17.
1333    (Thanks to Raymond Kumar and Alan Mintz.)  Assume for now that
1334    the later-than-usual start date is a one-time departure from the
1335    recent pattern.
1336
1337  Changes to build procedure
1338
1339    Rearguard tarballs now contain an empty file pacificnew.
1340    Some older downstream software expects this file to exist.
1341    (Problem reported by Mike Cullinan.)
1342
1343
1344Release 2020b - 2020-10-06 18:35:04 -0700
1345
1346  Briefly:
1347    Revised predictions for Morocco's changes starting in 2023.
1348    Canada's Yukon changes to -07 on 2020-11-01, not 2020-03-08.
1349    Macquarie Island has stayed in sync with Tasmania since 2011.
1350    Casey, Antarctica is at +08 in winter and +11 in summer.
1351    zic no longer supports -y, nor the TYPE field of Rules.
1352
1353  Changes to future timestamps
1354
1355    Morocco's spring-forward after Ramadan is now predicted to occur
1356    no sooner than two days after Ramadan, instead of one day.
1357    (Thanks to Milamber.)  The first altered prediction is for 2023,
1358    now predicted to spring-forward on April 30 instead of April 23.
1359
1360  Changes to past and future timestamps
1361
1362   Casey Station, Antarctica has been using +08 in winter and +11 in
1363   summer since 2018.  The most recent transition from +08 to +11 was
1364   2020-10-04 00:01.  Also, Macquarie Island has been staying in
1365   sync with Tasmania since 2011.  (Thanks to Steffen Thorsen.)
1366
1367  Changes to past and future time zone abbreviations and DST flags
1368
1369    Canada's Yukon, represented by America/Whitehorse and
1370    America/Dawson, changes its time zone rules from -08/-07 to
1371    permanent -07 on 2020-11-01, not on 2020-03-08 as 2020a had it.
1372    This change affects only the time zone abbreviation (MST vs PDT)
1373    and daylight saving flag for the period between the two dates.
1374    (Thanks to Andrew G. Smith.)
1375
1376  Changes to past timestamps
1377
1378    Correct several transitions for Hungary for 1918/1983.
1379    For example, the 1983-09-25 fall-back was at 01:00, not 03:00.
1380    (Thanks to Géza Nyáry.)  Also, the 1890 transition to standard
1381    time was on 11-01, not 10-01 (thanks to Michael Deckers).
1382
1383    The 1891 French transition was on March 16, not March 15.  The
1384    1911-03-11 French transition was at midnight, not a minute later.
1385    Monaco's transitions were on 1892-06-01 and 1911-03-29, not
1386    1891-03-15 and 1911-03-11.  (Thanks to Michael Deckers.)
1387
1388  Changes to code
1389
1390    Support for zic's long-obsolete '-y YEARISTYPE' option has been
1391    removed and, with it, so has support for the TYPE field in Rule
1392    lines, which is now reserved for compatibility with earlier zic.
1393    These features were previously deprecated in release 2015f.
1394    (Thanks to Tim Parenti.)
1395
1396    zic now defaults to '-b slim' instead of to '-b fat'.
1397
1398    zic's new '-l -' and '-p -' options uninstall any existing
1399    localtime and posixrules files, respectively.
1400
1401    The undocumented and ineffective tzsetwall function has been
1402    removed.
1403
1404  Changes to build procedure
1405
1406    The Makefile now defaults POSIXRULES to '-', so the posixrules
1407    feature (obsolete as of 2019b) is no longer installed by default.
1408
1409  Changes to documentation and commentary
1410
1411    The long-obsolete files pacificnew, systemv, and yearistype.sh have
1412    been removed from the distribution.  (Thanks to Tim Parenti.)
1413
1414
1415Release 2020a - 2020-04-23 16:03:47 -0700
1416
1417  Briefly:
1418    Morocco springs forward on 2020-05-31, not 2020-05-24.
1419    Canada's Yukon advanced to -07 year-round on 2020-03-08.
1420    America/Nuuk renamed from America/Godthab.
1421    zic now supports expiration dates for leap second lists.
1422
1423  Changes to future timestamps
1424
1425    Morocco's second spring-forward transition in 2020 will be May 31,
1426    not May 24 as predicted earlier.  (Thanks to Semlali Naoufal.)
1427    Adjust future-year predictions to use the first Sunday after the
1428    day after Ramadan, not the first Sunday after Ramadan.
1429
1430    Canada's Yukon, represented by America/Whitehorse and
1431    America/Dawson, advanced to -07 year-round, beginning with its
1432    spring-forward transition on 2020-03-08, and will not fall back on
1433    2020-11-01.  Although a government press release calls this
1434    "permanent Pacific Daylight Saving Time", we prefer MST for
1435    consistency with nearby Dawson Creek, Creston, and Fort Nelson.
1436    (Thanks to Tim Parenti.)
1437
1438  Changes to past timestamps
1439
1440    Shanghai observed DST in 1919.  (Thanks to Phake Nick.)
1441
1442  Changes to timezone identifiers
1443
1444    To reflect current usage in English better, America/Godthab has
1445    been renamed to America/Nuuk.  A backwards-compatibility link
1446    remains for the old name.
1447
1448  Changes to code
1449
1450    localtime.c no longer mishandles timestamps after the last
1451    transition in a TZif file with leap seconds and with daylight
1452    saving time transitions projected into the indefinite future.
1453    For example, with TZ='America/Los_Angeles' with leap seconds,
1454    zdump formerly reported a DST transition on 2038-03-14
1455    from 01:59:32.999... to 02:59:33 instead of the correct transition
1456    from 01:59:59.999... to 03:00:00.
1457
1458    zic -L now supports an Expires line in the leapseconds file, and
1459    truncates the TZif output accordingly.  This propagates leap
1460    second expiration information into the TZif file, and avoids the
1461    abovementioned localtime.c bug as well as similar bugs present in
1462    many client implementations.  If no Expires line is present, zic
1463    -L instead truncates the TZif output based on the #expires comment
1464    present in leapseconds files distributed by tzdb 2018f and later;
1465    however, this usage is obsolescent.  For now, the distributed
1466    leapseconds file has an Expires line that is commented out, so
1467    that the file can be fed to older versions of zic which ignore the
1468    commented-out line.  Future tzdb distributions are planned to
1469    contain a leapseconds file with an Expires line.
1470
1471    The configuration macros HAVE_TZNAME and USG_COMPAT should now be
1472    set to 1 if the system library supports the feature, and 2 if not.
1473    As before, these macros are nonzero if tzcode should support the
1474    feature, zero otherwise.
1475
1476    The configuration macro ALTZONE now has the same values with the
1477    same meaning as HAVE_TZNAME and USG_COMPAT.
1478
1479    The code's defense against CRLF in leap-seconds.list is now
1480    portable to POSIX awk.  (Problem reported by Deborah Goldsmith.)
1481
1482    Although the undocumented tzsetwall function is not changed in
1483    this release, it is now deprecated in preparation for removal in
1484    future releases.  Due to POSIX requirements, tzsetwall has not
1485    worked for some time.  Any code that uses it should instead use
1486    tzalloc(NULL) or, if portability trumps thread-safety, should
1487    unset the TZ environment variable.
1488
1489  Changes to commentary
1490
1491    The Îles-de-la-Madeleine and the Listuguj reserve are noted as
1492    following America/Halifax, and comments about Yukon's "south" and
1493    "north" have been corrected to say "east" and "west".  (Thanks to
1494    Jeffery Nichols.)
1495
1496
1497Release 2019c - 2019-09-11 08:59:48 -0700
1498
1499  Briefly:
1500    Fiji observes DST from 2019-11-10 to 2020-01-12.
1501    Norfolk Island starts observing Australian-style DST.
1502
1503  Changes to future timestamps
1504
1505    Fiji's next DST transitions will be 2019-11-10 and 2020-01-12
1506    instead of 2019-11-03 and 2020-01-19.  (Thanks to Raymond Kumar.)
1507    Adjust future guesses accordingly.
1508
1509    Norfolk Island will observe Australian-style DST starting in
1510    spring 2019.  The first transition is on 2019-10-06.  (Thanks to
1511    Kyle Czech and Michael Deckers.)
1512
1513  Changes to past timestamps
1514
1515    Many corrections to time in Turkey from 1940 through 1985.
1516    (Thanks to Oya Vulaş via Alois Treindl, and to Kıvanç Yazan.)
1517
1518    The Norfolk Island 1975-03-02 transition was at 02:00 standard
1519    time, not 02:00 DST.  (Thanks to Michael Deckers.)
1520
1521    South Korea observed DST from 1948 through 1951.  Although this
1522    info was supposed to appear in release 2014j, a typo inadvertently
1523    suppressed the change.  (Thanks to Alois Treindl.)
1524
1525    Detroit observed DST in 1967 and 1968 following the US DST rules,
1526    except that its 1967 DST began on June 14 at 00:01.  (Thanks to
1527    Alois Treindl for pointing out that the old data entries were
1528    probably wrong.)
1529
1530    Fix several errors in pre-1970 transitions in Perry County, IN.
1531    (Thanks to Alois Treindl for pointing out the 1967/9 errors.)
1532
1533    Edmonton did not observe DST in 1967 or 1969.  In 1946 Vancouver
1534    ended DST on 09-29 not 10-13, and Vienna ended DST on 10-07 not
1535    10-06.  In 1945 Königsberg (now Kaliningrad) switched from +01/+02
1536    to +02/+03 on 04-10 not 01-01, and its +02/+03 is abbreviated
1537    EET/EEST, not CET/CEST.  (Thanks to Alois Treindl.)  In 1946
1538    Königsberg switched to +03 on 04-07 not 01-01.
1539
1540    In 1946 Louisville switched from CST to CDT on 04-28 at 00:01, not
1541    01-01 at 00:00.  (Thanks to Alois Treindl and Michael Deckers.)
1542    Also, it switched from CST to CDT on 1950-04-30, not 1947-04-27.
1543
1544    The 1892-05-01 transition in Brussels was at 00:17:30, not at noon.
1545    (Thanks to Michael Deckers.)
1546
1547  Changes to past time zone abbreviations and DST flags
1548
1549    Hong Kong Winter Time, observed from 1941-10-01 to 1941-12-25,
1550    is now flagged as DST and is abbreviated HKWT not HKT.
1551
1552  Changes to code
1553
1554    leapseconds.awk now relies only on its input data, rather than
1555    also relying on its comments.  (Inspired by code from Dennis
1556    Ferguson and Chris Woodbury.)
1557
1558    The code now defends against CRLFs in leap-seconds.list.
1559    (Thanks to Brian Inglis and Chris Woodbury.)
1560
1561  Changes to documentation and commentary
1562
1563    theory.html discusses leap seconds.  (Thanks to Steve Summit.)
1564
1565    Nashville's newspapers dueled about the time of day in the 1950s.
1566    (Thanks to John Seigenthaler.)
1567
1568    Liechtenstein observed Swiss DST in 1941/2.
1569    (Thanks to Alois Treindl.)
1570
1571
1572Release 2019b - 2019-07-01 00:09:53 -0700
1573
1574  Briefly:
1575    Brazil no longer observes DST.
1576    'zic -b slim' outputs smaller TZif files; please try it out.
1577    Palestine's 2019 spring-forward transition was on 03-29, not 03-30.
1578
1579  Changes to future timestamps
1580
1581    Brazil has canceled DST and will stay on standard time indefinitely.
1582    (Thanks to Steffen Thorsen, Marcus Diniz, and Daniel Soares de
1583    Oliveira.)
1584
1585    Predictions for Morocco now go through 2087 instead of 2037, to
1586    work around a problem on newlib when using TZif files output by
1587    zic 2019a or earlier.  (Problem reported by David Gauchard.)
1588
1589  Changes to past and future timestamps
1590
1591    Palestine's 2019 spring transition was 03-29 at 00:00, not 03-30
1592    at 01:00.  (Thanks to Sharef Mustafa and Even Scharning.)  Guess
1593    future transitions to be March's last Friday at 00:00.
1594
1595  Changes to past timestamps
1596
1597    Hong Kong's 1941-06-15 spring-forward transition was at 03:00, not
1598    03:30.  Its 1945 transition from JST to HKT was on 11-18 at 02:00,
1599    not 09-15 at 00:00.  In 1946 its spring-forward transition was on
1600    04-21 at 00:00, not the previous day at 03:30.  From 1946 through
1601    1952 its fall-back transitions occurred at 04:30, not at 03:30.
1602    In 1947 its fall-back transition was on 11-30, not 12-30.
1603    (Thanks to P Chan.)
1604
1605  Changes to past time zone abbreviations
1606
1607    Italy's 1866 transition to Rome Mean Time was on December 12, not
1608    September 22.  This affects only the time zone abbreviation for
1609    Europe/Rome between those dates.  (Thanks to Stephen Trainor and
1610    Luigi Rosa.)
1611
1612  Changes affecting metadata only
1613
1614    Add info about the Crimea situation in zone1970.tab and zone.tab.
1615    (Problem reported by Serhii Demediuk.)
1616
1617  Changes to code
1618
1619    zic's new -b option supports a way to control data bloat and to
1620    test for year-2038 bugs in software that reads TZif files.
1621    'zic -b fat' and 'zic -b slim' generate larger and smaller output;
1622    for example, changing from fat to slim shrinks the Europe/London
1623    file from 3648 to 1599 bytes, saving about 56%.  Fat and slim
1624    files represent the same set of timestamps and use the same TZif
1625    format as documented in tzfile(5) and in Internet RFC 8536.
1626    Fat format attempts to work around bugs or incompatibilities in
1627    older software, notably software that mishandles 64-bit TZif data
1628    or uses obsolete TZ strings like "EET-2EEST" that lack DST rules.
1629    Slim format is more efficient and does not work around 64-bit bugs
1630    or obsolete TZ strings.  Currently zic defaults to fat format
1631    unless you compile with -DZIC_BLOAT_DEFAULT=\"slim\"; this
1632    out-of-the-box default is intended to change in future releases
1633    as the buggy software often mishandles timestamps anyway.
1634
1635    zic no longer treats a set of rules ending in 2037 specially.
1636    Previously, zic assumed that such a ruleset meant that future
1637    timestamps could not be predicted, and therefore omitted a
1638    POSIX-like TZ string in the TZif output.  The old behavior is no
1639    longer needed for current tzdata, and caused problems with newlib
1640    when used with older tzdata (reported by David Gauchard).
1641
1642    zic no longer generates some artifact transitions.  For example,
1643    Europe/London no longer has a no-op transition in January 1996.
1644
1645  Changes to build procedure
1646
1647    tzdata.zi now assumes zic 2017c or later.  This shrinks tzdata.zi
1648    by a percent or so.
1649
1650  Changes to documentation and commentary
1651
1652    The Makefile now documents the POSIXRULES macro as being obsolete,
1653    and similarly, zic's -p POSIXRULES option is now documented as
1654    being obsolete.  Although the POSIXRULES feature still exists and
1655    works as before, in practice it is rarely used for its intended
1656    purpose, and it does not work either in the default reference
1657    implementation (for timestamps after 2037) or in common
1658    implementations such as GNU/Linux (for contemporary timestamps).
1659    Since POSIXRULES was designed primarily as a temporary transition
1660    facility for System V platforms that died off decades ago, it is
1661    being decommissioned rather than institutionalized.
1662
1663    New info on Bonin Islands and Marcus (thanks to Wakaba and Phake Nick).
1664
1665
1666Release 2019a - 2019-03-25 22:01:33 -0700
1667
1668  Briefly:
1669    Palestine "springs forward" on 2019-03-30 instead of 2019-03-23.
1670    Metlakatla "fell back" to rejoin Alaska Time on 2019-01-20 at 02:00.
1671
1672  Changes to past and future timestamps
1673
1674    Palestine will not start DST until 2019-03-30, instead of 2019-03-23 as
1675    previously predicted.  Adjust our prediction by guessing that spring
1676    transitions will be between 24 and 30 March, which matches recent practice
1677    since 2016.  (Thanks to Even Scharning and Tim Parenti.)
1678
1679    Metlakatla ended its observance of Pacific standard time,
1680    rejoining Alaska Time, on 2019-01-20 at 02:00.  (Thanks to Ryan
1681    Stanley and Tim Parenti.)
1682
1683  Changes to past timestamps
1684
1685    Israel observed DST in 1980 (08-02/09-13) and 1984 (05-05/08-25).
1686    (Thanks to Alois Treindl and Isaac Starkman.)
1687
1688  Changes to time zone abbreviations
1689
1690    Etc/UCT is now a backward-compatibility link to Etc/UTC, instead
1691    of being a separate zone that generates the abbreviation "UCT",
1692    which nowadays is typically a typo.  (Problem reported by Isiah
1693    Meadows.)
1694
1695  Changes to code
1696
1697    zic now has an -r option to limit the time range of output data.
1698    For example, 'zic -r @1000000000' limits the output data to
1699    timestamps starting 1000000000 seconds after the Epoch.
1700    This helps shrink output size and can be useful for applications
1701    not needing the full timestamp history, such as TZDIST truncation;
1702    see Internet RFC 8536 section 5.1.  (Inspired by a feature request
1703    from Christopher Wong, helped along by bug reports from Wong and
1704    from Tim Parenti.)
1705
1706  Changes to documentation
1707
1708    Mention Internet RFC 8536 (February 2019), which documents TZif.
1709
1710    tz-link.html now cites tzdata-meta
1711    <https://tzdata-meta.timtimeonline.com/>.
1712
1713
1714Release 2018i - 2018-12-30 11:05:43 -0800
1715
1716  Briefly:
1717    São Tomé and Príncipe switches from +01 to +00 on 2019-01-01.
1718
1719  Changes to future timestamps
1720
1721    Due to a change in government, São Tomé and Príncipe switches back
1722    from +01 to +00 on 2019-01-01 at 02:00.  (Thanks to Vadim
1723    Nasardinov and Michael Deckers.)
1724
1725
1726Release 2018h - 2018-12-23 17:59:32 -0800
1727
1728  Briefly:
1729    Qyzylorda, Kazakhstan moved from +06 to +05 on 2018-12-21.
1730    New zone Asia/Qostanay because Qostanay, Kazakhstan didn't move.
1731    Metlakatla, Alaska observes PST this winter only.
1732    Guess Morocco will continue to adjust clocks around Ramadan.
1733    Add predictions for Iran from 2038 through 2090.
1734
1735  Changes to future timestamps
1736
1737    Guess that Morocco will continue to fall back just before and
1738    spring forward just after Ramadan, the practice since 2012.
1739    (Thanks to Maamar Abdelkader.)  This means Morocco will observe
1740    negative DST during Ramadan in main and vanguard formats, and in
1741    rearguard format it stays in the +00 timezone and observes
1742    ordinary DST in all months other than Ramadan.  As before, extend
1743    this guesswork to the year 2037.  As a consequence, Morocco is
1744    scheduled to observe three DST transitions in some Gregorian years
1745    (e.g., 2033) due to the mismatch between the Gregorian and Islamic
1746    calendars.
1747
1748    The table of exact transitions for Iranian DST has been extended.
1749    It formerly cut off before the year 2038 in a nod to 32-bit time_t.
1750    It now cuts off before 2091 as there is doubt about how the Persian
1751    calendar will treat 2091.  This change predicts DST transitions in
1752    2038-9, 2042-3, and 2046-7 to occur one day later than previously
1753    predicted.  As before, post-cutoff transitions are approximated.
1754
1755  Changes to past and future timestamps
1756
1757    Qyzylorda (aka Kyzylorda) oblast in Kazakhstan moved from +06 to
1758    +05 on 2018-12-21.  This is a zone split as Qostanay (aka
1759    Kostanay) did not switch, so create a zone Asia/Qostanay.
1760
1761    Metlakatla moved from Alaska to Pacific standard time on 2018-11-04.
1762    It did not change clocks that day and remains on -08 this winter.
1763    (Thanks to Ryan Stanley.)  It will revert to the usual Alaska
1764    rules next spring, so this change affects only timestamps
1765    from 2018-11-04 through 2019-03-10.
1766
1767  Change to past timestamps
1768
1769    Kwajalein's 1993-08-20 transition from -12 to +12 was at 24:00,
1770    not 00:00.  I transcribed the time incorrectly from Shanks.
1771    (Thanks to Phake Nick.)
1772
1773    Nauru's 1979 transition was on 02-10 at 02:00, not 05-01 at 00:00.
1774    (Thanks to Phake Nick.)
1775
1776    Guam observed DST irregularly from 1959 through 1977.
1777    (Thanks to Phake Nick.)
1778
1779    Hong Kong observed DST in 1941 starting 06-15 (not 04-01), then on
1780    10-01 changed standard time to +08:30 (not +08).  Its transition
1781    back to +08 after WWII was on 1945-09-15, not the previous day.
1782    Its 1904-10-30 change took effect at 01:00 +08 (not 00:00 LMT).
1783    (Thanks to Phake Nick, Steve Allen, and Joseph Myers.)  Also,
1784    its 1952 fallback was on 11-02 (not 10-25).
1785
1786    This release contains many changes to timestamps before 1946 due
1787    to Japanese possession or occupation of Pacific/Chuuk,
1788    Pacific/Guam, Pacific/Kosrae, Pacific/Kwajalein, Pacific/Majuro,
1789    Pacific/Nauru, Pacific/Palau, and Pacific/Pohnpei.
1790    (Thanks to Phake Nick.)
1791
1792    Assume that the Spanish East Indies was like the Philippines and
1793    observed American time until the end of 1844.  This affects
1794    Pacific/Chuuk, Pacific/Kosrae, Pacific/Palau, and Pacific/Pohnpei.
1795
1796  Changes to past tm_isdst flags
1797
1798    For the recent Morocco change, the tm_isdst flag should be 1 from
1799    2018-10-27 00:00 to 2018-10-28 03:00.  (Thanks to Michael Deckers.)
1800    Give a URL to the official decree.  (Thanks to Matt Johnson.)
1801
1802
1803Release 2018g - 2018-10-26 22:22:45 -0700
1804
1805  Briefly:
1806    Morocco switches to permanent +01 on 2018-10-28.
1807
1808  Changes to future timestamps
1809
1810    Morocco switches from +00/+01 to permanent +01 effective 2018-10-28,
1811    so its clocks will not fall back as previously scheduled.
1812    (Thanks to Mohamed Essedik Najd and Brian Inglis.)
1813
1814  Changes to code
1815
1816    When generating TZif files with leap seconds, zic no longer uses a
1817    format that trips up older 32-bit clients, fixing a bug introduced
1818    in 2018f.  (Reported by Daniel Fischer.)  Also, the zic workaround
1819    for QTBUG-53071 now also works for TZif files with leap seconds.
1820
1821    The translator to rearguard format now rewrites the line
1822    "Rule Japan 1948 1951 - Sep Sat>=8 25:00 0 S" to
1823    "Rule Japan 1948 1951 - Sep Sun>=9  1:00 0 S".
1824    This caters to zic before 2007 and to Oracle TZUpdater 2.2.0
1825    and earlier.  (Reported by Christos Zoulas.)
1826
1827  Changes to past time zone abbreviations
1828
1829    Change HDT to HWT/HPT for WWII-era abbreviations in Hawaii.
1830    This reverts to 2011h, as the abbreviation change in 2011i was
1831    likely inadvertent.
1832
1833  Changes to documentation
1834
1835    tzfile.5 has new sections on interoperability issues.
1836
1837
1838Release 2018f - 2018-10-18 00:14:18 -0700
1839
1840  Briefly:
1841  Volgograd moves from +03 to +04 on 2018-10-28.
1842  Fiji ends DST 2019-01-13, not 2019-01-20.
1843  Most of Chile changes DST dates, effective 2019-04-06.
1844
1845  Changes to future timestamps
1846
1847    Volgograd moves from +03 to +04 on 2018-10-28 at 02:00.
1848    (Thanks to Alexander Fetisov and Stepan Golosunov.)
1849
1850    Fiji ends DST 2019-01-13 instead of the 2019-01-20 previously
1851    predicted.  (Thanks to Raymond Kumar.)  Adjust future predictions
1852    accordingly.
1853
1854    Most of Chile will end DST on the first Saturday in April at 24:00 mainland
1855    time, and resume DST on the first Saturday in September at 24:00 mainland
1856    time.  The changes are effective from 2019-04-06, and do not affect the
1857    Magallanes region modeled by America/Punta_Arenas.  (Thanks to Juan Correa
1858    and Tim Parenti.)  Adjust future predictions accordingly.
1859
1860  Changes to past timestamps
1861
1862    The 2018-05-05 North Korea 30-minute time zone change took place
1863    at 23:30 the previous day, not at 00:00 that day.
1864
1865    China's 1988 spring-forward transition was on April 17, not
1866    April 10.  Its DST transitions in 1986/91 were at 02:00, not 00:00.
1867    (Thanks to P Chan.)
1868
1869    Fix several issues for Macau before 1992.  Macau's pre-1904 LMT
1870    was off by 10 s.  Macau switched to +08 in 1904 not 1912, and
1871    temporarily switched to +09/+10 during World War II.  Macau
1872    observed DST in 1942/79, not 1961/80, and there were several
1873    errors for transition times and dates.  (Thanks to P Chan.)
1874
1875    The 1948-1951 fallback transitions in Japan were at 25:00 on
1876    September's second Saturday, not at 24:00.  (Thanks to Phake Nick.)
1877    zic turns this into 01:00 on the day after September's second
1878    Saturday, which is the best that POSIX or C platforms can do.
1879
1880    Incorporate 1940-1949 Asia/Shanghai DST transitions from a 2014
1881    paper by Li Yu, replacing more-questionable data from Shanks.
1882
1883  Changes to time zone abbreviations
1884
1885    Use "PST" and "PDT" for Philippine time.  (Thanks to Paul Goyette.)
1886
1887  Changes to code
1888
1889    zic now always generates TZif files where time type 0 is used for
1890    timestamps before the first transition.  This simplifies the
1891    reading of TZif files and should not affect behavior of existing
1892    TZif readers because the same set of time types is used; only
1893    their internal indexes may have changed.  This affects only the
1894    legacy zones EST5EDT, CST6CDT, MST7MDT, PST8PDT, CET, MET, and
1895    EET, which previously used nonzero types for these timestamps.
1896
1897    Because of the type 0 change, zic no longer outputs a dummy
1898    transition at time -2**59 (before the Big Bang), as clients should
1899    no longer need this to handle historical timestamps correctly.
1900    This reverts a change introduced in 2013d and shrinks most TZif
1901    files by a few bytes.
1902
1903    zic now supports negative time-of-day in Rule and Leap lines, e.g.,
1904    "Rule X min max - Apr lastSun -6:00 1:00 -" means the transition
1905    occurs at 18:00 on the Saturday before the last Sunday in April.
1906    This behavior was documented in 2018a but the code did not
1907    entirely match the documentation.
1908
1909    localtime.c no longer requires at least one time type in TZif
1910    files that lack transitions or have a POSIX-style TZ string.  This
1911    future-proofs the code against possible future extensions to the
1912    format that would allow TZif files with POSIX-style TZ strings and
1913    without transitions or time types.
1914
1915    A read-access subscript error in localtime.c has been fixed.
1916    It could occur only in TZif files with timecnt == 0, something that
1917    does not happen in practice now but could happen in future versions.
1918
1919    localtime.c no longer ignores TZif POSIX-style TZ strings that
1920    specify only standard time.  Instead, these TZ strings now
1921    override the default time type for timestamps after the last
1922    transition (or for all timestamps if there are no transitions),
1923    just as DST strings specifying DST have always done.
1924
1925    leapseconds.awk now outputs "#updated" and "#expires" comments,
1926    and supports leap seconds at the ends of months other than June
1927    and December.  (Inspired by suggestions from Chris Woodbury.)
1928
1929  Changes to documentation
1930
1931    New restrictions: A Rule name must start with a character that
1932    is neither an ASCII digit nor "-" nor "+", and an unquoted name
1933    should not use characters in the set "!$%&'()*,/:;<=>?@[\]^`{|}~".
1934    The latter restriction makes room for future extensions (a
1935    possibility noted by Tom Lane).
1936
1937    tzfile.5 now documents what time types apply before the first and
1938    after the last transition, if any.
1939
1940    Documentation now uses the spelling "timezone" for a TZ setting
1941    that determines timestamp history, and "time zone" for a
1942    geographic region currently sharing the same standard time.
1943
1944    The name "TZif" is now used for the tz binary data format.
1945
1946    tz-link.htm now mentions the A0 TimeZone Migration utilities.
1947    (Thanks to Aldrin Martoq for the link.)
1948
1949  Changes to build procedure
1950
1951    New 'make' target 'rearguard_tarballs' to build the rearguard
1952    tarball only.  This is a convenience on platforms that lack lzip
1953    if you want to build the rearguard tarball.  (Problem reported by
1954    Deborah Goldsmith.)
1955
1956    tzdata.zi is now more stable from release to release.  (Problem
1957    noted by Tom Lane.)  It is also a bit shorter.
1958
1959    tzdata.zi now can contain comment lines documenting configuration
1960    information, such as which data format was selected, which input
1961    files were used, and how leap seconds are treated.  (Problems
1962    noted by Lester Caine and Brian Inglis.)  If the Makefile defaults
1963    are used these comment lines are absent, for backward
1964    compatibility.  A redistributor intending to alter its copy of the
1965    files should also append "-LABEL" to the 'version' file's first
1966    line, where "LABEL" identifies the redistributor's change.
1967
1968
1969Release 2018e - 2018-05-01 23:42:51 -0700
1970
1971  Briefly:
1972
1973    North Korea switches back to +09 on 2018-05-05.
1974    The main format uses negative DST again, for Ireland etc.
1975    'make tarballs' now also builds a rearguard tarball.
1976    New 's' and 'd' suffixes in SAVE columns of Rule and Zone lines.
1977
1978  Changes to past and future timestamps
1979
1980    North Korea switches back from +0830 to +09 on 2018-05-05.
1981    (Thanks to Kang Seonghoon, Arthur David Olson, Seo Sanghyeon,
1982    and Tim Parenti.)
1983
1984    Bring back the negative-DST changes of 2018a, except be more
1985    compatible with data parsers that do not support negative DST.
1986    Also, this now affects historical timestamps in Namibia and the
1987    former Czechoslovakia, not just Ireland.  The main format now uses
1988    negative DST to model timestamps in Europe/Dublin (from 1971 on),
1989    Europe/Prague (1946/7), and Africa/Windhoek (1994/2017).  This
1990    does not affect UT offsets, only time zone abbreviations and the
1991    tm_isdst flag.  Also, this does not affect rearguard or vanguard
1992    formats; effectively the main format now uses vanguard instead of
1993    rearguard format.  Data parsers that do not support negative DST
1994    can still use data from the rearguard tarball described below.
1995
1996  Changes to build procedure
1997
1998    The command 'make tarballs' now also builds the tarball
1999    tzdataVERSION-rearguard.tar.gz, which is like tzdataVERSION.tar.gz
2000    except that it uses rearguard format intended for trailing-edge
2001    data parsers.
2002
2003  Changes to data format and to code
2004
2005    The SAVE column of Rule and Zone lines can now have an 's' or 'd'
2006    suffix, which specifies whether the adjusted time is standard time
2007    or daylight saving time.  If no suffix is given, daylight saving
2008    time is used if and only if the SAVE column is nonzero; this is
2009    the longstanding behavior.  Although this new feature is not used
2010    in tzdata, it could be used to specify the legal time in Namibia
2011    1994-2017, as opposed to the popular time (see below).
2012
2013  Changes to past timestamps
2014
2015    From 1994 through 2017 Namibia observed DST in winter, not summer.
2016    That is, it used negative DST, as Ireland still does.  This change
2017    does not affect UTC offsets; it affects only the tm_isdst flag and
2018    the abbreviation used during summer, which is now CAT, not WAST.
2019    Although (as noted by Michael Deckers) summer and winter time were
2020    both simply called "standard time" in Namibian law, in common
2021    practice winter time was considered to be DST (as noted by Stephen
2022    Colebourne).  The full effect of this change is only in vanguard
2023    and main format; in rearguard format, the tm_isdst flag is still
2024    zero in winter and nonzero in summer.
2025
2026    In 1946/7 Czechoslovakia also observed negative DST in winter.
2027    The full effect of this change is only in vanguard and main
2028    formats; in rearguard format, it is modeled as plain GMT without
2029    daylight saving.  Also, the dates of some 1944/5 DST transitions
2030    in Czechoslovakia have been changed.
2031
2032
2033Release 2018d - 2018-03-22 07:05:46 -0700
2034
2035  Briefly:
2036
2037  Palestine starts DST a week earlier in 2018.
2038  Add support for vanguard and rearguard data consumers.
2039  Add subsecond precision to source data format, though not to data.
2040
2041  Changes to future timestamps
2042
2043    In 2018, Palestine starts DST on March 24, not March 31.
2044    Adjust future predictions accordingly.  (Thanks to Sharef Mustafa.)
2045
2046  Changes to past and future timestamps
2047
2048    Casey Station in Antarctica changed from +11 to +08 on 2018-03-11
2049    at 04:00.  (Thanks to Steffen Thorsen.)
2050
2051  Changes to past timestamps
2052
2053    Historical transitions for Uruguay, represented by
2054    America/Montevideo, have been updated per official legal documents,
2055    replacing previous data mainly originating from the inventions of
2056    Shanks & Pottenger.  This has resulted in adjustments ranging from
2057    30 to 90 minutes in either direction over at least two dozen
2058    distinct periods ranging from one day to several years in length.
2059    A mere handful of pre-1991 transitions are unaffected; data since
2060    then has come from more reliable contemporaneous reporting.  These
2061    changes affect various timestamps in 1920-1923, 1936, 1939,
2062    1942-1943, 1959, 1966-1970, 1972, 1974-1980, and 1988-1990.
2063    Additionally, Uruguay's pre-standard-time UT offset has been
2064    adjusted westward by 7 seconds, from UT-03:44:44 to UT-03:44:51, to
2065    match the location of the Observatory of the National Meteorological
2066    Institute in Montevideo.
2067    (Thanks to Jeremie Bonjour, Tim Parenti, and Michael Deckers.)
2068
2069    East Kiribati skipped New Year's Eve 1994, not New Year's Day 1995.
2070    (Thanks to Kerry Shetline.)
2071
2072    Fix the 1912-01-01 transition for Portugal and its colonies.
2073    This transition was at 00:00 according to the new UT offset, not
2074    according to the old one.  Also assume that Cape Verde switched on
2075    the same date as the rest, not in 1907.  This affects
2076    Africa/Bissau, Africa/Sao_Tome, Asia/Macau, Atlantic/Azores,
2077    Atlantic/Cape_Verde, Atlantic/Madeira, and Europe/Lisbon.
2078    (Thanks to Michael Deckers.)
2079
2080    Fix an off-by-1 error for pre-1913 timestamps in Jamaica and in
2081    Turks & Caicos.
2082
2083  Changes to past time zone abbreviations
2084
2085    MMT took effect in Uruguay from 1908-06-10, not 1898-06-28.  There
2086    is no clock change associated with the transition.
2087
2088  Changes to build procedure
2089
2090    The new DATAFORM macro in the Makefile lets the installer choose
2091    among three source data formats.  The idea is to lessen downstream
2092    disruption when data formats are improved.
2093
2094    * DATAFORM=vanguard installs from the latest, bleeding-edge
2095      format.  DATAFORM=main (the default) installs from the format
2096      used in the 'africa' etc. files.  DATAFORM=rearguard installs
2097      from a trailing-edge format.  Eventually, elements of today's
2098      vanguard format should move to the main format, and similarly
2099      the main format's features should eventually move to the
2100      rearguard format.
2101
2102    * In the current version, the main and rearguard formats are
2103      identical and match that of 2018c, so this change does not
2104      affect default behavior.  The vanguard format currently contains
2105      one feature not in the main format: negative SAVE values.  This
2106      improves support for Ireland, which uses Irish Standard Time
2107      (IST, UTC+01) in summer and GMT (UTC) in winter.  tzcode has
2108      supported negative SAVE values for decades, and this feature
2109      should move to the main format soon.  However, it will not move
2110      to the rearguard format for quite some time because some
2111      downstream parsers do not support it.
2112
2113    * The build procedure constructs three files vanguard.zi, main.zi,
2114      and rearguard.zi, one for each format.  Although the files
2115      represent essentially the same data, they may have minor
2116      discrepancies that users are not likely to notice.  The files
2117      are intended for downstream data consumers and are not
2118      installed.  Zoneinfo parsers that do not support negative SAVE values
2119      should start using rearguard.zi, so that they will be unaffected
2120      when the negative-DST feature moves from vanguard to main.
2121      Bleeding-edge Zoneinfo parsers that support the new features
2122      already can use vanguard.zi; in this respect, current tzcode is
2123      bleeding-edge.
2124
2125    The Makefile should now be safe for parallelized builds, and 'make
2126    -j to2050new.tzs' is now much faster on a multiprocessor host
2127    with GNU Make.
2128
2129    When built with -DSUPPRESS_TZDIR, the tzcode library no longer
2130    prepends TZDIR/ to file names that do not begin with '/'.  This is
2131    not recommended for general use, due to its security implications.
2132    (From a suggestion by Manuela Friedrich.)
2133
2134  Changes to code
2135
2136    zic now accepts subsecond precision in expressions like
2137    00:19:32.13, which is approximately the legal time of the
2138    Netherlands from 1835 to 1937.  However, because it is
2139    questionable whether the few recorded uses of non-integer offsets
2140    had subsecond precision in practice, there are no plans for tzdata
2141    to use this feature.  (Thanks to Steve Allen for pointing out
2142    the limitations of historical data in this area.)
2143
2144    The code is a bit more portable to MS-Windows.  Installers can
2145    compile with -DRESERVE_STD_EXT_IDS on MS-Windows platforms that
2146    reserve identifiers like 'localtime'.  (Thanks to Manuela
2147    Friedrich.)
2148
2149  Changes to documentation and commentary
2150
2151    theory.html now outlines tzdb's extensions to POSIX's model for
2152    civil time, and has a section "POSIX features no longer needed"
2153    that lists POSIX API components that are now vestigial.
2154    (From suggestions by Steve Summit.)  It also better distinguishes
2155    time zones from tz regions.  (From a suggestion by Guy Harris.)
2156
2157    Commentary is now more consistent about using the phrase "daylight
2158    saving time", to match the C name tm_isdst.  Daylight saving time
2159    need not occur in summer, and need not have a positive offset from
2160    standard time.
2161
2162    Commentary about historical transitions in Uruguay has been expanded
2163    with links to many relevant legal documents.
2164    (Thanks to Tim Parenti.)
2165
2166    Commentary now uses some non-ASCII characters with Unicode value
2167    less than U+0100, as they can be useful and should work even with
2168    older editors such as XEmacs.
2169
2170
2171Release 2018c - 2018-01-22 23:00:44 -0800
2172
2173  Briefly:
2174  Revert Irish changes that relied on negative SAVE values.
2175
2176  Changes to tm_isdst
2177
2178    Revert the 2018a change to Europe/Dublin.  As before, this change
2179    does not affect UT offsets or abbreviations; it affects only
2180    whether timestamps are considered to be standard time or
2181    daylight-saving time, as expressed in the tm_isdst flag of C's
2182    struct tm type.  This reversion is intended to be a temporary
2183    workaround for problems discovered with downstream uses of
2184    releases 2018a and 2018b, which implemented Irish time by using
2185    negative SAVE values in the Eire rules of the 'europe' file.
2186    Although negative SAVE values have been part of tzcode for many
2187    years and are supported by many platforms, they were not
2188    documented before 2018a and ICU and OpenJDK do not currently
2189    support them.  A mechanism to export data to platforms lacking
2190    support for negative DST is planned to be developed before the
2191    change is reapplied.  (Problems reported by Deborah Goldsmith and
2192    Stephen Colebourne.)
2193
2194  Changes to past timestamps
2195
2196    Japanese DST transitions (1948-1951) were Sundays at 00:00, not
2197    Saturdays or Sundays at 02:00.  (Thanks to Takayuki Nikai.)
2198
2199  Changes to build procedure
2200
2201    The build procedure now works around mawk 1.3.3's lack of support
2202    for character class expressions.  (Problem reported by Ohyama.)
2203
2204
2205Release 2018b - 2018-01-17 23:24:48 -0800
2206
2207  Briefly:
2208  Fix a packaging problem in tz2018a, which was missing 'pacificnew'.
2209
2210  Changes to build procedure
2211
2212    The distribution now contains the file 'pacificnew' again.
2213    This file was inadvertently omitted in the 2018a distribution.
2214    (Problem reported by Matias Fonzo.)
2215
2216
2217Release 2018a - 2018-01-12 22:29:21 -0800
2218
2219  Briefly:
2220  São Tomé and Príncipe switched from +00 to +01.
2221  Brazil's DST will now start on November's first Sunday.
2222  Ireland's standard time is now in the summer, not the winter.
2223  Use Debian-style installation locations, instead of 4.3BSD-style.
2224  New zic option -t.
2225
2226  Changes to past and future timestamps
2227
2228    São Tomé and Príncipe switched from +00 to +01 on 2018-01-01 at
2229    01:00.  (Thanks to Steffen Thorsen and Michael Deckers.)
2230
2231  Changes to future timestamps
2232
2233    Starting in 2018 southern Brazil will begin DST on November's
2234    first Sunday instead of October's third Sunday.  (Thanks to
2235    Steffen Thorsen.)
2236
2237  Changes to past timestamps
2238
2239    A discrepancy of 4 s in timestamps before 1931 in South Sudan has
2240    been corrected.  The 'backzone' and 'zone.tab' files did not agree
2241    with the 'africa' and 'zone1970.tab' files.  (Problem reported by
2242    Michael Deckers.)
2243
2244    The abbreviation invented for Bolivia Summer Time (1931-2) is now
2245    BST instead of BOST, to be more consistent with the convention
2246    used for Latvian Summer Time (1918-9) and for British Summer Time.
2247
2248  Changes to tm_isdst
2249
2250    Change Europe/Dublin so that it observes Irish Standard Time (UT
2251    +01) in summer and GMT (as negative daylight-saving) in winter,
2252    instead of observing standard time (GMT) in winter and Irish
2253    Summer Time (UT +01) in summer.  This change does not affect UT
2254    offsets or abbreviations; it affects only whether timestamps are
2255    considered to be standard time or daylight-saving time, as
2256    expressed in the tm_isdst flag of C's struct tm type.
2257    (Discrepancy noted by Derick Rethans.)
2258
2259  Changes to build procedure
2260
2261    The default installation locations have been changed to mostly
2262    match Debian circa 2017, instead of being designed as an add-on to
2263    4.3BSD circa 1986.  This affects the Makefile macros TOPDIR,
2264    TZDIR, MANDIR, and LIBDIR.  New Makefile macros TZDEFAULT, USRDIR,
2265    USRSHAREDIR, BINDIR, ZDUMPDIR, and ZICDIR let installers tailor
2266    locations more precisely.  (This responds to suggestions from
2267    Brian Inglis and from Steve Summit.)
2268
2269    The default installation procedure no longer creates the
2270    backward-compatibility link US/Pacific-New, which causes
2271    confusion during user setup (e.g., see Debian bug 815200).
2272    Use 'make BACKWARD="backward pacificnew"' to create the link
2273    anyway, for now.  Eventually we plan to remove the link entirely.
2274
2275    tzdata.zi now contains a version-number comment.
2276    (Suggested by Tom Lane.)
2277
2278    The Makefile now quotes values like BACKWARD more carefully when
2279    passing them to the shell.  (Problem reported by Zefram.)
2280
2281    Builders no longer need to specify -DHAVE_SNPRINTF on platforms
2282    that have snprintf and use pre-C99 compilers.  (Problem reported
2283    by Jon Skeet.)
2284
2285  Changes to code
2286
2287    zic has a new option -t FILE that specifies the location of the
2288    file that determines local time when TZ is unset.  The default for
2289    this location can be configured via the new TZDEFAULT makefile
2290    macro, which defaults to /etc/localtime.
2291
2292    Diagnostics and commentary now distinguish UT from UTC more
2293    carefully; see theory.html for more information about UT vs UTC.
2294
2295    zic has been ported to GCC 8's -Wstringop-truncation option.
2296    (Problem reported by Martin Sebor.)
2297
2298  Changes to documentation and commentary
2299
2300    The zic man page now documents the longstanding behavior that
2301    times and years can be out of the usual range, with negative times
2302    counting backwards from midnight and with year 0 preceding year 1.
2303    (Problem reported by Michael Deckers.)
2304
2305    The theory.html file now mentions the POSIX limit of six chars
2306    per abbreviation, and lists alphabetic abbreviations used.
2307
2308    The files tz-art.htm and tz-link.htm have been renamed to
2309    tz-art.html and tz-link.html, respectively, for consistency with
2310    other file names and to simplify web server configuration.
2311
2312
2313Release 2017c - 2017-10-20 14:49:34 -0700
2314
2315  Briefly:
2316  Northern Cyprus switches from +03 to +02/+03 on 2017-10-29.
2317  Fiji ends DST 2018-01-14, not 2018-01-21.
2318  Namibia switches from +01/+02 to +02 on 2018-04-01.
2319  Sudan switches from +03 to +02 on 2017-11-01.
2320  Tonga likely switches from +13/+14 to +13 on 2017-11-05.
2321  Turks & Caicos switches from -04 to -05/-04 on 2018-11-04.
2322  A new file tzdata.zi now holds a small text copy of all data.
2323  The zic input format has been regularized slightly.
2324
2325  Changes to future timestamps
2326
2327    Northern Cyprus has decided to resume EU rules starting
2328    2017-10-29, thus reinstituting winter time.
2329
2330    Fiji ends DST 2018-01-14 instead of the 2018-01-21 previously
2331    predicted.  (Thanks to Dominic Fok.)  Adjust future predictions
2332    accordingly.
2333
2334    Namibia will switch from +01 with DST to +02 all year on
2335    2017-09-03 at 02:00.  This affects UT offsets starting 2018-04-01
2336    at 02:00.  (Thanks to Steffen Thorsen.)
2337
2338    Sudan will switch from +03 to +02 on 2017-11-01.  (Thanks to Ahmed
2339    Atyya and Yahia Abdalla.)  South Sudan is not switching, so
2340    Africa/Juba is no longer a link to Africa/Khartoum.
2341
2342    Tonga has likely ended its experiment with DST, and will not
2343    adjust its clocks on 2017-11-05.  Although Tonga has not announced
2344    whether it will continue to observe DST, the IATA is assuming that
2345    it will not.  (Thanks to David Wade.)
2346
2347    Turks & Caicos will switch from -04 all year to -05 with US DST on
2348    2018-03-11 at 03:00.  This affects UT offsets starting 2018-11-04
2349    at 02:00.  (Thanks to Steffen Thorsen.)
2350
2351  Changes to past timestamps
2352
2353    Namibia switched from +02 to +01 on 1994-03-21, not 1994-04-03.
2354    (Thanks to Arthur David Olson.)
2355
2356    Detroit did not observe DST in 1967.
2357
2358    Use railway time for Asia/Kolkata before 1941, by switching to
2359    Madras local time (UT +052110) in 1870, then to IST (UT +0530) in
2360    1906.  Also, treat 1941-2's +0630 as DST, like 1942-5.
2361
2362    Europe/Dublin's 1946 and 1947 fallback transitions occurred at
2363    02:00 standard time, not 02:00 DST.  (Thanks to Michael Deckers.)
2364
2365    Pacific/Apia and Pacific/Pago_Pago switched from Antipodean to
2366    American time in 1892, not 1879.  (Thanks to Michael Deckers.)
2367
2368    Adjust the 1867 transition in Alaska to better reflect the
2369    historical record, by changing it to occur on 1867-10-18 at 15:30
2370    Sitka time rather than at the start of 1867-10-17 local time.
2371    Although strictly speaking this is accurate only for Sitka,
2372    the rest of Alaska's blanks need to be filled in somehow.
2373
2374    Fix off-by-one errors in UT offsets for Adak and Nome before 1867.
2375    (Thanks to Michael Deckers.)
2376
2377    Add 7 s to the UT offset in Asia/Yangon before 1920.
2378
2379  Changes to zone names
2380
2381    Remove Canada/East-Saskatchewan from the 'backward' file, as it
2382    exceeded the 14-character limit and was an unused misnomer anyway.
2383
2384  Changes to build procedure
2385
2386    To support applications that prefer to read time zone data in text
2387    form, two zic input files tzdata.zi and leapseconds are now
2388    installed by default.  The commands 'zic tzdata.zi' and 'zic -L
2389    leapseconds tzdata.zi' can reproduce the tzdata binary files
2390    without and with leap seconds, respectively.  To prevent these two
2391    new files from being installed, use 'make TZDATA_TEXT=', and to
2392    suppress leap seconds from the tzdata text installation, use 'make
2393    TZDATA_TEXT=tzdata.zi'.
2394
2395    'make BACKWARD=' now suppresses backward-compatibility names
2396    like 'US/Pacific' that are defined in the 'backward' and
2397    'pacificnew' files.
2398
2399    'make check' now works on systems that lack a UTF-8 locale,
2400    or that lack the nsgmls program.  Set UTF8_LOCALE to configure
2401    the name of a UTF-8 locale, if you have one.
2402
2403    Y2K runtime checks are no longer enabled by default.  Add
2404    -DDEPRECATE_TWO_DIGIT_YEARS to CFLAGS to enable them, instead of
2405    adding -DNO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
2406    to disable them.  (New name suggested by Brian Inglis.)
2407
2408    The build procedure for zdump now works on AIX 7.1.
2409    (Problem reported by Kees Dekker.)
2410
2411  Changes to code
2412
2413    zic and the reference runtime now reject multiple leap seconds
2414    within 28 days of each other, or leap seconds before the Epoch.
2415    As a result, support for double leap seconds, which was
2416    obsolescent and undocumented, has been removed.  Double leap
2417    seconds were an error in the C89 standard; they have never existed
2418    in civil timekeeping.  (Thanks to Robert Elz and Bradley White for
2419    noticing glitches in the code that uncovered this problem.)
2420
2421    zic now warns about use of the obsolescent and undocumented -y
2422    option, and about use of the obsolescent TYPE field of Rule lines.
2423
2424    zic now allows unambiguous abbreviations like "Sa" and "Su" for
2425    weekdays; formerly it rejected them due to a bug.  Conversely, zic
2426    no longer considers non-prefixes to be abbreviations; for example,
2427    it no longer accepts "lF" as an abbreviation for "lastFriday".
2428    Also, zic warns about the undocumented usage with a "last-"
2429    prefix, e.g., "last-Fri".
2430
2431    Similarly, zic now accepts the unambiguous abbreviation "L" for
2432    "Link" in ordinary context and for "Leap" in leap-second context.
2433    Conversely, zic no longer accepts non-prefixes such as "La" as
2434    abbreviations for words like "Leap".
2435
2436    zic no longer accepts leap second lines in ordinary input, or
2437    ordinary lines in leap second input.  Formerly, zic sometimes
2438    warned about this undocumented usage and handled it incorrectly.
2439
2440    The new macro HAVE_TZNAME governs whether the tzname external
2441    variable is exported, instead of USG_COMPAT.  USG_COMPAT now
2442    governs only the external variables "timezone" and "daylight".
2443    This change is needed because the three variables are not in the
2444    same category: although POSIX requires tzname, it specifies the
2445    other two variables as optional.  Also, USG_COMPAT is now 1 or 0:
2446    if not defined, the code attempts to guess it from other macros.
2447
2448    localtime.c and difftime.c no longer require stdio.h, and .c files
2449    other than zic.c no longer require sys/wait.h.
2450
2451    zdump.c no longer assumes snprintf.  (Reported by Jonathan Leffler.)
2452
2453    Calculation of time_t extrema works around a bug in GCC 4.8.4
2454    (Reported by Stan Shebs and Joseph Myers.)
2455
2456    zic.c no longer mistranslates formats of line numbers in non-English
2457    locales.  (Problem reported by Benno Schulenberg.)
2458
2459    Several minor changes have been made to the code to make it a
2460    bit easier to port to MS-Windows and Solaris.  (Thanks to Kees
2461    Dekker for reporting the problems.)
2462
2463  Changes to documentation and commentary
2464
2465    The two new files 'theory.html' and 'calendars' contain the
2466    contents of the removed file 'Theory'.  The goal is to document
2467    tzdb theory more accessibly.
2468
2469    The zic man page now documents abbreviation rules.
2470
2471    tz-link.htm now covers how to apply tzdata changes to clients.
2472    (Thanks to Jorge Fábregas for the AIX link.)  It also mentions MySQL.
2473
2474    The leap-seconds.list URL has been updated to something that is
2475    more reliable for tzdb.  (Thanks to Tim Parenti and Brian Inglis.)
2476
2477Release 2017b - 2017-03-17 07:30:38 -0700
2478
2479  Briefly: Haiti has resumed DST.
2480
2481  Changes to past and future timestamps
2482
2483    Haiti resumed observance of DST in 2017.  (Thanks to Steffen Thorsen.)
2484
2485  Changes to past timestamps
2486
2487    Liberia changed from -004430 to +00 on 1972-01-07, not 1972-05-01.
2488
2489    Use "MMT" to abbreviate Liberia's time zone before 1972, as "-004430"
2490    is one byte over the POSIX limit.  (Problem reported by Derick Rethans.)
2491
2492  Changes to code
2493
2494    The reference localtime implementation now falls back on the
2495    current US daylight-saving transition rules rather than the
2496    1987-2006 rules.  This fallback occurs only when (1) the TZ
2497    environment variable has a value like "AST4ADT" that asks
2498    for daylight saving time but does not specify the rules, (2) there
2499    is no file by that name, and (3) the TZDEFRULES file cannot be
2500    loaded.  (Thanks to Tom Lane.)
2501
2502
2503Release 2017a - 2017-02-28 00:05:36 -0800
2504
2505  Briefly: Southern Chile moves from -04/-03 to -03, and Mongolia
2506  discontinues DST.
2507
2508  Changes to future timestamps
2509
2510    Mongolia no longer observes DST.  (Thanks to Ganbold Tsagaankhuu.)
2511
2512    Chile's Region of Magallanes moves from -04/-03 to -03 year-round.
2513    Its clocks diverge from America/Santiago starting 2017-05-13 at
2514    23:00, hiving off a new zone America/Punta_Arenas.  Although the
2515    Chilean government says this change expires in May 2019, for now
2516    assume it's permanent.  (Thanks to Juan Correa and Deborah
2517    Goldsmith.)  This also affects Antarctica/Palmer.
2518
2519  Changes to past timestamps
2520
2521    Fix many entries for historical timestamps for Europe/Madrid
2522    before 1979, to agree with tables compiled by Pere Planesas of the
2523    National Astronomical Observatory of Spain.  As a side effect,
2524    this changes some timestamps for Africa/Ceuta before 1929, which
2525    are probably guesswork anyway.  (Thanks to Steve Allen and
2526    Pierpaolo Bernardi for the heads-ups, and to Michael Deckers for
2527    correcting the 1901 transition.)
2528
2529    Ecuador observed DST from 1992-11-28 to 1993-02-05.
2530    (Thanks to Alois Treindl.)
2531
2532    Asia/Atyrau and Asia/Oral were at +03 (not +04) before 1930-06-21.
2533    (Thanks to Stepan Golosunov.)
2534
2535  Changes to past and future time zone abbreviations
2536
2537    Switch to numeric time zone abbreviations for South America, as
2538    part of the ongoing project of removing invented abbreviations.
2539    This avoids the need to invent an abbreviation for the new Chilean
2540    new zone.  Similarly, switch from invented to numeric time zone
2541    abbreviations for Afghanistan, American Samoa, the Azores,
2542    Bangladesh, Bhutan, the British Indian Ocean Territory, Brunei,
2543    Cape Verde, Chatham Is, Christmas I, Cocos (Keeling) Is, Cook Is,
2544    Dubai, East Timor, Eucla, Fiji, French Polynesia, Greenland,
2545    Indochina, Iran, Iraq, Kiribati, Lord Howe, Macquarie, Malaysia,
2546    the Maldives, Marshall Is, Mauritius, Micronesia, Mongolia,
2547    Myanmar, Nauru, Nepal, New Caledonia, Niue, Norfolk I, Palau,
2548    Papua New Guinea, the Philippines, Pitcairn, Qatar, Réunion, St
2549    Pierre & Miquelon, Samoa, Saudi Arabia, Seychelles, Singapore,
2550    Solomon Is, Tokelau, Tuvalu, Wake, Vanuatu, Wallis & Futuna, and
2551    Xinjiang; for 20-minute daylight saving time in Ghana before 1943;
2552    for half-hour daylight saving time in Belize before 1944 and in
2553    the Dominican Republic before 1975; and for Canary Islands before
2554    1946, for Guinea-Bissau before 1975, for Iceland before 1969, for
2555    Indian Summer Time before 1942, for Indonesia before around 1964,
2556    for Kenya before 1960, for Liberia before 1973, for Madeira before
2557    1967, for Namibia before 1943, for the Netherlands in 1937-9, for
2558    Pakistan before 1971, for Western Sahara before 1977, and for
2559    Zaporozhye in 1880-1924.
2560
2561    For Alaska time from 1900 through 1967, instead of "CAT" use the
2562    abbreviation "AST", the abbreviation commonly used at the time
2563    (Atlantic Standard Time had not been standardized yet).  Use "AWT"
2564    and "APT" instead of the invented abbreviations "CAWT" and "CAPT".
2565
2566    Use "CST" and "CDT" instead of invented abbreviations for Macau
2567    before 1999 and Taiwan before 1938, and use "JST" instead of the
2568    invented abbreviation "JCST" for Japan and Korea before 1938.
2569
2570  Change to database entry category
2571
2572    Move the Pacific/Johnston link from 'australasia' to 'backward',
2573    since Johnston is now uninhabited.
2574
2575  Changes to code
2576
2577    zic no longer mishandles some transitions in January 2038 when it
2578    attempts to work around Qt bug 53071.  This fixes a bug affecting
2579    Pacific/Tongatapu that was introduced in zic 2016e.  localtime.c
2580    now contains a workaround, useful when loading a file generated by
2581    a buggy zic.  (Problem and localtime.c fix reported by Bradley
2582    White.)
2583
2584    zdump -i now outputs non-hour numeric time zone abbreviations
2585    without a colon, e.g., "+0530" rather than "+05:30".  This agrees
2586    with zic %z and with common practice, and simplifies auditing of
2587    zdump output.
2588
2589    zdump is now buildable again with -DUSE_LTZ=0.
2590    (Problem reported by Joseph Myers.)
2591
2592    zdump.c now always includes private.h, to avoid code duplication
2593    with private.h.  (Problem reported by Kees Dekker.)
2594
2595    localtime.c no longer mishandles early or late timestamps
2596    when TZ is set to a POSIX-style string that specifies DST.
2597    (Problem reported by Kees Dekker.)
2598
2599    date and strftime now cause %z to generate "-0000" instead of
2600    "+0000" when the UT offset is zero and the time zone abbreviation
2601    begins with "-".
2602
2603  Changes to documentation and commentary
2604
2605    The 'Theory' file now better documents choice of historical time
2606    zone abbreviations.  (Problems reported by Michael Deckers.)
2607
2608    tz-link.htm now covers leap smearing, which is popular in clouds.
2609
2610
2611Release 2016j - 2016-11-22 23:17:13 -0800
2612
2613  Briefly: Saratov, Russia moves from +03 to +04 on 2016-12-04.
2614
2615  Changes to future timestamps
2616
2617    Saratov, Russia switches from +03 to +04 on 2016-12-04 at 02:00.
2618    This hives off a new zone Europe/Saratov from Europe/Volgograd.
2619    (Thanks to Yuri Konotopov and Stepan Golosunov.)
2620
2621  Changes to past timestamps
2622
2623    The new zone Asia/Atyrau for Atyraū Region, Kazakhstan, is like
2624    Asia/Aqtau except it switched from +05/+06 to +04/+05 in spring
2625    1999, not fall 1994.  (Thanks to Stepan Golosunov.)
2626
2627  Changes to past time zone abbreviations
2628
2629    Asia/Gaza and Asia/Hebron now use "EEST", not "EET", to denote
2630    summer time before 1948.  The old use of "EET" was a typo.
2631
2632  Changes to code
2633
2634    zic no longer mishandles file systems that lack hard links, fixing
2635    bugs introduced in 2016g.  (Problems reported by Tom Lane.)
2636    Also, when the destination already contains symbolic links, zic
2637    should now work better on systems where the 'link' system call
2638    does not follow symbolic links.
2639
2640  Changes to documentation and commentary
2641
2642    tz-link.htm now documents the relationship between release version
2643    numbers and development-repository commit tags.  (Suggested by
2644    Paul Koning.)
2645
2646    The 'Theory' file now documents UT.
2647
2648    iso3166.tab now accents "Curaçao", and commentary now mentions
2649    the names "Cabo Verde" and "Czechia".  (Thanks to Jiří Boháč.)
2650
2651
2652Release 2016i - 2016-11-01 23:19:52 -0700
2653
2654  Briefly: Cyprus split into two time zones on 2016-10-30, and Tonga
2655  reintroduces DST on 2016-11-06.
2656
2657  Changes to future timestamps
2658
2659    Pacific/Tongatapu begins DST on 2016-11-06 at 02:00, ending on
2660    2017-01-15 at 03:00.  Assume future observances in Tonga will be
2661    from the first Sunday in November through the third Sunday in
2662    January, like Fiji.  (Thanks to Pulu ʻAnau.)  Switch to numeric
2663    time zone abbreviations for this zone.
2664
2665  Changes to past and future timestamps
2666
2667    Northern Cyprus is now +03 year round, causing a split in Cyprus
2668    time zones starting 2016-10-30 at 04:00.  This creates a zone
2669    Asia/Famagusta.  (Thanks to Even Scharning and Matt Johnson.)
2670
2671    Antarctica/Casey switched from +08 to +11 on 2016-10-22.
2672    (Thanks to Steffen Thorsen.)
2673
2674  Changes to past timestamps
2675
2676    Several corrections were made for pre-1975 timestamps in Italy.
2677    These affect Europe/Malta, Europe/Rome, Europe/San_Marino, and
2678    Europe/Vatican.
2679
2680    First, the 1893-11-01 00:00 transition in Italy used the new UT
2681    offset (+01), not the old (+00:49:56).  (Thanks to Michael
2682    Deckers.)
2683
2684    Second, rules for daylight saving in Italy were changed to agree
2685    with Italy's National Institute of Metrological Research (INRiM)
2686    except for 1944, as follows (thanks to Pierpaolo Bernardi, Brian
2687    Inglis, and Michael Deckers):
2688
2689      The 1916-06-03 transition was at 24:00, not 00:00.
2690
2691      The 1916-10-01, 1919-10-05, and 1920-09-19 transitions were at
2692      00:00, not 01:00.
2693
2694      The 1917-09-30 and 1918-10-06 transitions were at 24:00, not
2695      01:00.
2696
2697      The 1944-09-17 transition was at 03:00, not 01:00.  This
2698      particular change is taken from Italian law as INRiM's table,
2699      (which says 02:00) appears to have a typo here.  Also, keep the
2700      1944-04-03 transition for Europe/Rome, as Rome was controlled by
2701      Germany then.
2702
2703      The 1967-1970 and 1972-1974 fallback transitions were at 01:00,
2704      not 00:00.
2705
2706  Changes to code
2707
2708    The code should now be buildable on AmigaOS merely by setting the
2709    appropriate Makefile variables.  (From a patch by Carsten Larsen.)
2710
2711
2712Release 2016h - 2016-10-19 23:17:57 -0700
2713
2714  Changes to future timestamps
2715
2716    Asia/Gaza and Asia/Hebron end DST on 2016-10-29 at 01:00, not
2717    2016-10-21 at 00:00.  (Thanks to Sharef Mustafa.)  Predict that
2718    future fall transitions will be on the last Saturday of October
2719    at 01:00, which is consistent with predicted spring transitions
2720    on the last Saturday of March.  (Thanks to Tim Parenti.)
2721
2722  Changes to past timestamps
2723
2724    In Turkey, transitions in 1986-1990 were at 01:00 standard time
2725    not at 02:00, and the spring 1994 transition was on March 20, not
2726    March 27.  (Thanks to Kıvanç Yazan.)
2727
2728  Changes to past and future time zone abbreviations
2729
2730    Asia/Colombo now uses numeric time zone abbreviations like "+0530"
2731    instead of alphabetic ones like "IST" and "LKT".  Various
2732    English-language sources use "IST", "LKT" and "SLST", with no
2733    working consensus.  (Usage of "SLST" mentioned by Sadika
2734    Sumanapala.)
2735
2736  Changes to code
2737
2738    zic no longer mishandles relativizing file names when creating
2739    symbolic links like /etc/localtime, when these symbolic links
2740    are outside the usual directory hierarchy.  This fixes a bug
2741    introduced in 2016g.  (Problem reported by Andreas Stieger.)
2742
2743  Changes to build procedure
2744
2745    New rules 'traditional_tarballs' and 'traditional_signatures' for
2746    building just the traditional-format distribution.  (Requested by
2747    Deborah Goldsmith.)
2748
2749    The file 'version' is now put into the tzdata tarball too.
2750    (Requested by Howard Hinnant.)
2751
2752  Changes to documentation and commentary
2753
2754    The 'Theory' file now has a section on interface stability.
2755    (Requested by Paul Koning.)  It also mentions features like
2756    tm_zone and localtime_rz that have long been supported by the
2757    reference code.
2758
2759    tz-link.htm has improved coverage of time zone boundaries suitable
2760    for geolocation.  (Thanks to heads-ups from Evan Siroky and Matt
2761    Johnson.)
2762
2763    The US commentary now mentions Allen and the "day of two noons".
2764
2765    The Fiji commentary mentions the government's 2016-10-03 press
2766    release.  (Thanks to Raymond Kumar.)
2767
2768
2769Release 2016g - 2016-09-13 08:56:38 -0700
2770
2771  Changes to future timestamps
2772
2773    Turkey switched from EET/EEST (+02/+03) to permanent +03,
2774    effective 2016-09-07.  (Thanks to Burak AYDIN.)  Use "+03" rather
2775    than an invented abbreviation for the new time.
2776
2777    New leap second 2016-12-31 23:59:60 UTC as per IERS Bulletin C 52.
2778    (Thanks to Tim Parenti.)
2779
2780  Changes to past timestamps
2781
2782    For America/Los_Angeles, spring-forward transition times have been
2783    corrected from 02:00 to 02:01 in 1948, and from 02:00 to 01:00 in
2784    1950-1966.
2785
2786    For zones using Soviet time on 1919-07-01, transitions to UT-based
2787    time were at 00:00 UT, not at 02:00 local time.  The affected
2788    zones are Europe/Kirov, Europe/Moscow, Europe/Samara, and
2789    Europe/Ulyanovsk.  (Thanks to Alexander Belopolsky.)
2790
2791  Changes to past and future time zone abbreviations
2792
2793    The Factory zone now uses the time zone abbreviation -00 instead
2794    of a long English-language string, as -00 is now the normal way to
2795    represent an undefined time zone.
2796
2797    Several zones in Antarctica and the former Soviet Union, along
2798    with zones intended for ships at sea that cannot use POSIX TZ
2799    strings, now use numeric time zone abbreviations instead of
2800    invented or obsolete alphanumeric abbreviations.  The affected
2801    zones are Antarctica/Casey, Antarctica/Davis,
2802    Antarctica/DumontDUrville, Antarctica/Mawson, Antarctica/Rothera,
2803    Antarctica/Syowa, Antarctica/Troll, Antarctica/Vostok,
2804    Asia/Anadyr, Asia/Ashgabat, Asia/Baku, Asia/Bishkek, Asia/Chita,
2805    Asia/Dushanbe, Asia/Irkutsk, Asia/Kamchatka, Asia/Khandyga,
2806    Asia/Krasnoyarsk, Asia/Magadan, Asia/Omsk, Asia/Sakhalin,
2807    Asia/Samarkand, Asia/Srednekolymsk, Asia/Tashkent, Asia/Tbilisi,
2808    Asia/Ust-Nera, Asia/Vladivostok, Asia/Yakutsk, Asia/Yekaterinburg,
2809    Asia/Yerevan, Etc/GMT-14, Etc/GMT-13, Etc/GMT-12, Etc/GMT-11,
2810    Etc/GMT-10, Etc/GMT-9, Etc/GMT-8, Etc/GMT-7, Etc/GMT-6, Etc/GMT-5,
2811    Etc/GMT-4, Etc/GMT-3, Etc/GMT-2, Etc/GMT-1, Etc/GMT+1, Etc/GMT+2,
2812    Etc/GMT+3, Etc/GMT+4, Etc/GMT+5, Etc/GMT+6, Etc/GMT+7, Etc/GMT+8,
2813    Etc/GMT+9, Etc/GMT+10, Etc/GMT+11, Etc/GMT+12, Europe/Kaliningrad,
2814    Europe/Minsk, Europe/Samara, Europe/Volgograd, and
2815    Indian/Kerguelen.  For Europe/Moscow the invented abbreviation MSM
2816    was replaced by +05, whereas MSK and MSD were kept as they are not
2817    our invention and are widely used.
2818
2819  Changes to zone names
2820
2821    Rename Asia/Rangoon to Asia/Yangon, with a backward compatibility link.
2822    (Thanks to David Massoud.)
2823
2824  Changes to code
2825
2826    zic no longer generates binary files containing POSIX TZ-like
2827    strings that disagree with the local time type after the last
2828    explicit transition in the data.  This fixes a bug with
2829    Africa/Casablanca and Africa/El_Aaiun in some year-2037 timestamps
2830    on the reference platform.  (Thanks to Alexander Belopolsky for
2831    reporting the bug and suggesting a way forward.)
2832
2833    If the installed localtime and/or posixrules files are symbolic
2834    links, zic now keeps them symbolic links when updating them, for
2835    compatibility with platforms like OpenSUSE where other programs
2836    configure these files as symlinks.
2837
2838    zic now avoids hard linking to symbolic links, avoids some
2839    unnecessary mkdir and stat system calls, and uses shorter file
2840    names internally.
2841
2842    zdump has a new -i option to generate transitions in a
2843    smaller but still human-readable format.  This option is
2844    experimental, and the output format may change in future versions.
2845    (Thanks to Jon Skeet for suggesting that an option was needed,
2846    and thanks to Tim Parenti and Chris Rovick for further comments.)
2847
2848  Changes to build procedure
2849
2850    An experimental distribution format is available, in addition
2851    to the traditional format which will continue to be distributed.
2852    The new format is a tarball tzdb-VERSION.tar.lz with signature
2853    file tzdb-VERSION.tar.lz.asc.  It unpacks to a top-level directory
2854    tzdb-VERSION containing the code and data of the traditional
2855    two-tarball format, along with extra data that may be useful.
2856    (Thanks to Antonio Diaz Diaz, Oscar van Vlijmen, and many others
2857    for comments about the experimental format.)
2858
2859    The release version number is now more accurate in the usual case
2860    where releases are built from a Git repository.  For example, if
2861    23 commits and some working-file changes have been made since
2862    release 2016g, the version number is now something like
2863    '2016g-23-g50556e3-dirty' instead of the misleading '2016g'.
2864    Tagged releases use the same version number format as before,
2865    e.g., '2016g'.  To support the more accurate version number, its
2866    specification has moved from a line in the Makefile to a new
2867    source file 'version'.
2868
2869    The experimental distribution contains a file to2050.tzs that
2870    contains what should be the output of 'zdump -i -c 2050' on
2871    primary zones.  If this file is available, 'make check' now checks
2872    that zdump generates this output.
2873
2874    'make check_web' now works on Fedora-like distributions.
2875
2876  Changes to documentation and commentary
2877
2878    tzfile.5 now documents the new restriction on POSIX TZ-like
2879    strings that is now implemented by zic.
2880
2881    Comments now cite URLs for some 1917-1921 Russian DST decrees.
2882    (Thanks to Alexander Belopolsky.)
2883
2884    tz-link.htm mentions JuliaTime (thanks to Curtis Vogt) and Time4J
2885    (thanks to Meno Hochschild) and ThreeTen-Extra, and its
2886    description of Java 8 has been brought up to date (thanks to
2887    Stephen Colebourne).  Its description of local time on Mars has
2888    been updated to match current practice, and URLs have been updated
2889    and some obsolete ones removed.
2890
2891
2892Release 2016f - 2016-07-05 16:26:51 +0200
2893
2894  Changes affecting future timestamps
2895
2896    The Egyptian government changed its mind on short notice, and
2897    Africa/Cairo will not introduce DST starting 2016-07-07 after all.
2898    (Thanks to Mina Samuel.)
2899
2900    Asia/Novosibirsk switches from +06 to +07 on 2016-07-24 at 02:00.
2901    (Thanks to Stepan Golosunov.)
2902
2903  Changes to past and future timestamps
2904
2905    Asia/Novokuznetsk and Asia/Novosibirsk now use numeric time zone
2906    abbreviations instead of invented ones.
2907
2908  Changes affecting past timestamps
2909
2910    Europe/Minsk's 1992-03-29 spring-forward transition was at 02:00 not 00:00.
2911    (Thanks to Stepan Golosunov.)
2912
2913
2914Release 2016e - 2016-06-14 08:46:16 -0700
2915
2916  Changes affecting future timestamps
2917
2918    Africa/Cairo observes DST in 2016 from July 7 to the end of October.
2919    Guess October 27 and 24:00 transitions.  (Thanks to Steffen Thorsen.)
2920    For future years, guess April's last Thursday to October's last
2921    Thursday except for Ramadan.
2922
2923  Changes affecting past timestamps
2924
2925    Locations while uninhabited now use '-00', not 'zzz', as a
2926    placeholder time zone abbreviation.  This is inspired by Internet
2927    RFC 3339 and is more consistent with numeric time zone
2928    abbreviations already used elsewhere.  The change affects several
2929    arctic and antarctic locations, e.g., America/Cambridge_Bay before
2930    1920 and Antarctica/Troll before 2005.
2931
2932    Asia/Baku's 1992-09-27 transition from +04 (DST) to +04 (non-DST) was
2933    at 03:00, not 23:00 the previous day.  (Thanks to Michael Deckers.)
2934
2935  Changes to code
2936
2937    zic now outputs a dummy transition at time 2**31 - 1 in zones
2938    whose POSIX-style TZ strings contain a '<'.  This mostly works
2939    around Qt bug 53071 <https://bugreports.qt.io/browse/QTBUG-53071>.
2940    (Thanks to Zhanibek Adilbekov for reporting the Qt bug.)
2941
2942  Changes affecting documentation and commentary
2943
2944    tz-link.htm says why governments should give plenty of notice for
2945    time zone or DST changes, and refers to Matt Johnson's blog post.
2946
2947    tz-link.htm mentions Tzdata for Elixir.  (Thanks to Matt Johnson.)
2948
2949
2950Release 2016d - 2016-04-17 22:50:29 -0700
2951
2952  Changes affecting future timestamps
2953
2954    America/Caracas switches from -0430 to -04 on 2016-05-01 at 02:30.
2955    (Thanks to Alexander Krivenyshev for the heads-up.)
2956
2957    Asia/Magadan switches from +10 to +11 on 2016-04-24 at 02:00.
2958    (Thanks to Alexander Krivenyshev and Matt Johnson.)
2959
2960    New zone Asia/Tomsk, split off from Asia/Novosibirsk.  It covers
2961    Tomsk Oblast, Russia, which switches from +06 to +07 on 2016-05-29
2962    at 02:00.  (Thanks to Stepan Golosunov.)
2963
2964  Changes affecting past timestamps
2965
2966    New zone Europe/Kirov, split off from Europe/Volgograd.  It covers
2967    Kirov Oblast, Russia, which switched from +04/+05 to +03/+04 on
2968    1989-03-26 at 02:00, roughly a year after Europe/Volgograd made
2969    the same change.  (Thanks to Stepan Golosunov.)
2970
2971    Russia and nearby locations had daylight-saving transitions on
2972    1992-03-29 at 02:00 and 1992-09-27 at 03:00, instead of on
2973    1992-03-28 at 23:00 and 1992-09-26 at 23:00.  (Thanks to Stepan
2974    Golosunov.)
2975
2976    Many corrections to historical time in Kazakhstan from 1991
2977    through 2005.  (Thanks to Stepan Golosunov.)  Replace Kazakhstan's
2978    invented time zone abbreviations with numeric abbreviations.
2979
2980  Changes to commentary
2981
2982    Mention Internet RFCs 7808 (TZDIST) and 7809 (CalDAV time zone references).
2983
2984
2985Release 2016c - 2016-03-23 00:51:27 -0700
2986
2987  Changes affecting future timestamps
2988
2989    Azerbaijan no longer observes DST.  (Thanks to Steffen Thorsen.)
2990
2991    Chile reverts from permanent to seasonal DST.  (Thanks to Juan
2992    Correa for the heads-up, and to Tim Parenti for corrections.)
2993    Guess that future transitions are August's and May's second
2994    Saturdays at 24:00 mainland time.  Also, call the period from
2995    2014-09-07 through 2016-05-14 daylight saving time instead of
2996    standard time, as that seems more appropriate now.
2997
2998  Changes affecting past timestamps
2999
3000    Europe/Kaliningrad and Europe/Vilnius changed from +03/+04 to
3001    +02/+03 on 1989-03-26, not 1991-03-31.  Europe/Volgograd changed
3002    from +04/+05 to +03/+04 on 1988-03-27, not 1989-03-26.
3003    (Thanks to Stepan Golosunov.)
3004
3005  Changes to commentary
3006
3007    Several updates and URLs for historical and proposed Russian changes.
3008    (Thanks to Stepan Golosunov, Matt Johnson, and Alexander Krivenyshev.)
3009
3010
3011Release 2016b - 2016-03-12 17:30:14 -0800
3012
3013  Compatibility note
3014
3015    Starting with release 2016b, some data entries cause zic implementations
3016    derived from tz releases 2005j through 2015e to issue warnings like
3017    "time zone abbreviation differs from POSIX standard (+03)".
3018    These warnings should not otherwise affect zic's output and can safely be
3019    ignored on today's platforms, as the warnings refer to a restriction in
3020    POSIX.1-1988 that was removed in POSIX.1-2001.  One way to suppress the
3021    warnings is to upgrade to zic derived from tz releases 2015f and later.
3022
3023  Changes affecting future timestamps
3024
3025    New zones Europe/Astrakhan and Europe/Ulyanovsk for Astrakhan and
3026    Ulyanovsk Oblasts, Russia, both of which will switch from +03 to +04 on
3027    2016-03-27 at 02:00 local time.  They need distinct zones since their
3028    post-1970 histories disagree.  New zone Asia/Barnaul for Altai Krai and
3029    Altai Republic, Russia, which will switch from +06 to +07 on the same date
3030    and local time.  The Astrakhan change is already official; the others have
3031    passed the first reading in the State Duma and are extremely likely.
3032    Also, Asia/Sakhalin moves from +10 to +11 on 2016-03-27 at 02:00.
3033    (Thanks to Alexander Krivenyshev for the heads-up, and to Matt Johnson
3034    and Stepan Golosunov for followup.)
3035
3036    As a trial of a new system that needs less information to be made up,
3037    the new zones use numeric time zone abbreviations like "+04"
3038    instead of invented abbreviations like "ASTT".
3039
3040    Haiti will not observe DST in 2016.  (Thanks to Jean Antoine via
3041    Steffen Thorsen.)
3042
3043    Palestine's spring-forward transition on 2016-03-26 is at 01:00, not 00:00.
3044    (Thanks to Hannah Kreitem.) Guess future transitions will be March's last
3045    Saturday at 01:00, not March's last Friday at 24:00.
3046
3047  Changes affecting past timestamps
3048
3049    Europe/Chisinau observed DST during 1990, and switched from +04 to
3050    +03 at 1990-05-06 02:00, instead of switching from +03 to +02.
3051    (Thanks to Stepan Golosunov.)
3052
3053    1991 abbreviations in Europe/Samara should be SAMT/SAMST, not
3054    KUYT/KUYST.  (Thanks to Stepan Golosunov.)
3055
3056  Changes to code
3057
3058    tzselect's diagnostics and checking, and checktab.awk's checking,
3059    have been improved.  (Thanks to J William Piggott.)
3060
3061    tzcode now builds under MinGW.  (Thanks to Ian Abbott and Esben Haabendal.)
3062
3063    tzselect now tests Julian-date TZ settings more accurately.
3064    (Thanks to J William Piggott.)
3065
3066  Changes to commentary
3067
3068    Comments in zone tables have been improved.  (Thanks to J William Piggott.)
3069
3070    tzselect again limits its menu comments so that menus fit on a
3071    24×80 alphanumeric display.
3072
3073    A new web page tz-how-to.html.  (Thanks to Bill Seymour.)
3074
3075    In the Theory file, the description of possible time zone abbreviations in
3076    tzdata has been cleaned up, as the old description was unclear and
3077    inconsistent.  (Thanks to Alain Mouette for reporting the problem.)
3078
3079
3080Release 2016a - 2016-01-26 23:28:02 -0800
3081
3082  Changes affecting future timestamps
3083
3084    America/Cayman will not observe daylight saving this year after all.
3085    Revert our guess that it would.  (Thanks to Matt Johnson.)
3086
3087    Asia/Chita switches from +0800 to +0900 on 2016-03-27 at 02:00.
3088    (Thanks to Alexander Krivenyshev.)
3089
3090    Asia/Tehran now has DST predictions for the year 2038 and later,
3091    to be March 21 00:00 to September 21 00:00.  This is likely better
3092    than predicting no DST, albeit off by a day every now and then.
3093
3094  Changes affecting past and future timestamps
3095
3096    America/Metlakatla switched from PST all year to AKST/AKDT on
3097    2015-11-01 at 02:00.  (Thanks to Steffen Thorsen.)
3098
3099    America/Santa_Isabel has been removed, and replaced with a
3100    backward compatibility link to America/Tijuana.  Its contents were
3101    apparently based on a misreading of Mexican legislation.
3102
3103  Changes affecting past timestamps
3104
3105    Asia/Karachi's two transition times in 2002 were off by a minute.
3106    (Thanks to Matt Johnson.)
3107
3108  Changes affecting build procedure
3109
3110    An installer can now combine leap seconds with use of the backzone file,
3111    e.g., with 'make PACKRATDATA=backzone REDO=posix_right zones'.
3112    The old 'make posix_packrat' rule is now marked as obsolescent.
3113    (Thanks to Ian Abbott for an initial implementation.)
3114
3115  Changes affecting documentation and commentary
3116
3117    A new file LICENSE makes it easier to see that the code and data
3118    are mostly public-domain.  (Thanks to James Knight.)  The three
3119    non-public-domain files now use the current (3-clause) BSD license
3120    instead of older versions of that license.
3121
3122    tz-link.htm mentions the BDE library (thanks to Andrew Paprocki),
3123    CCTZ (thanks to Tim Parenti), TimeJones.com, and has a new section
3124    on editing tz source files (with a mention of Sublime zoneinfo,
3125    thanks to Gilmore Davidson).
3126
3127    The Theory and asia files now mention the 2015 book "The Global
3128    Transformation of Time, 1870-1950", and cite a couple of reviews.
3129
3130    The America/Chicago entry now documents the informal use of US
3131    central time in Fort Pierre, South Dakota.  (Thanks to Rick
3132    McDermid, Matt Johnson, and Steve Jones.)
3133
3134
3135Release 2015g - 2015-10-01 00:39:51 -0700
3136
3137  Changes affecting future timestamps
3138
3139    Turkey's 2015 fall-back transition is scheduled for Nov. 8, not Oct. 25.
3140    (Thanks to Fatih.)
3141
3142    Norfolk moves from +1130 to +1100 on 2015-10-04 at 02:00 local time.
3143    (Thanks to Alexander Krivenyshev.)
3144
3145    Fiji's 2016 fall-back transition is scheduled for January 17, not 24.
3146    (Thanks to Ken Rylander.)
3147
3148    Fort Nelson, British Columbia will not fall back on 2015-11-01.  It has
3149    effectively been on MST (-0700) since it advanced its clocks on 2015-03-08.
3150    New zone America/Fort_Nelson.  (Thanks to Matt Johnson.)
3151
3152  Changes affecting past timestamps
3153
3154    Norfolk observed DST from 1974-10-27 02:00 to 1975-03-02 02:00.
3155
3156  Changes affecting code
3157
3158    localtime no longer mishandles America/Anchorage after 2037.
3159    (Thanks to Bradley White for reporting the bug.)
3160
3161    On hosts with signed 32-bit time_t, localtime no longer mishandles
3162    Pacific/Fiji after 2038-01-16 14:00 UTC.
3163
3164    The localtime module allows the variables 'timezone', 'daylight',
3165    and 'altzone' to be in common storage shared with other modules,
3166    and declares them in case the system <time.h> does not.
3167    (Problems reported by Kees Dekker.)
3168
3169    On platforms with tm_zone, strftime.c now assumes it is not NULL.
3170    This simplifies the code and is consistent with zdump.c.
3171    (Problem reported by Christos Zoulas.)
3172
3173  Changes affecting documentation
3174
3175   The tzfile man page now documents that transition times denote the
3176   starts (not the ends) of the corresponding time periods.
3177   (Ambiguity reported by Bill Seymour.)
3178
3179
3180Release 2015f - 2015-08-10 18:06:56 -0700
3181
3182  Changes affecting future timestamps
3183
3184    North Korea switches to +0830 on 2015-08-15.  (Thanks to Steffen Thorsen.)
3185    The abbreviation remains "KST".  (Thanks to Robert Elz.)
3186
3187    Uruguay no longer observes DST.  (Thanks to Steffen Thorsen
3188    and Pablo Camargo.)
3189
3190  Changes affecting past and future timestamps
3191
3192    Moldova starts and ends DST at 00:00 UTC, not at 01:00 UTC.
3193    (Thanks to Roman Tudos.)
3194
3195  Changes affecting data format and code
3196
3197    zic's '-y YEARISTYPE' option is no longer documented.  The TYPE
3198    field of a Rule line should now be '-'; the old values 'even',
3199    'odd', 'uspres', 'nonpres', 'nonuspres' were already undocumented.
3200    Although the implementation has not changed, these features do not
3201    work in the default installation, they are not used in the data,
3202    and they are now considered obsolescent.
3203
3204    zic now checks that two rules don't take effect at the same time.
3205    (Thanks to Jon Skeet and Arthur David Olson.)  Constraints on
3206    simultaneity are now documented.
3207
3208    The two characters '%z' in a zone format now stand for the UT
3209    offset, e.g., '-07' for seven hours behind UT and '+0530' for
3210    five hours and thirty minutes ahead.  This better supports time
3211    zone abbreviations conforming to POSIX.1-2001 and later.
3212
3213  Changes affecting installed data files
3214
3215    Comments for America/Halifax and America/Glace_Bay have been improved.
3216    (Thanks to Brian Inglis.)
3217
3218    Data entries have been simplified for Atlantic/Canary, Europe/Simferopol,
3219    Europe/Sofia, and Europe/Tallinn.  This yields slightly smaller
3220    installed data files for Europe/Simferopol and Europe/Tallinn.
3221    It does not affect timestamps.  (Thanks to Howard Hinnant.)
3222
3223  Changes affecting code
3224
3225    zdump and zic no longer warn about valid time zone abbreviations
3226    like '-05'.
3227
3228    Some Visual Studio 2013 warnings have been suppressed.
3229    (Thanks to Kees Dekker.)
3230
3231    'date' no longer sets the time of day and its -a, -d, -n and -t
3232    options have been removed.  Long obsolescent, the implementation
3233    of these features had porting problems.  Builders no longer need
3234    to configure HAVE_ADJTIME, HAVE_SETTIMEOFDAY, or HAVE_UTMPX_H.
3235    (Thanks to Kees Dekker for pointing out the problem.)
3236
3237  Changes affecting documentation
3238
3239    The Theory file mentions naming issues earlier, as these seem to be
3240    poorly publicized (thanks to Gilmore Davidson for reporting the problem).
3241
3242    tz-link.htm mentions Time Zone Database Parser (thanks to Howard Hinnant).
3243
3244    Mention that Herbert Samuel introduced the term "Summer Time".
3245
3246
3247Release 2015e - 2015-06-13 10:56:02 -0700
3248
3249  Changes affecting future timestamps
3250
3251    Morocco will suspend DST from 2015-06-14 03:00 through 2015-07-19 02:00,
3252    not 06-13 and 07-18 as we had guessed.  (Thanks to Milamber.)
3253
3254    Assume Cayman Islands will observe DST starting next year, using US rules.
3255    Although it isn't guaranteed, it is the most likely.
3256
3257  Changes affecting data format
3258
3259    The file 'iso3166.tab' now uses UTF-8, so that its entries can better
3260    spell the names of Åland Islands, Côte d'Ivoire, and Réunion.
3261
3262  Changes affecting code
3263
3264    When displaying data, tzselect converts it to the current locale's
3265    encoding if the iconv command works.  (Problem reported by random832.)
3266
3267    tzselect no longer mishandles Dominica, fixing a bug introduced
3268    in Release 2014f.  (Problem reported by Owen Leibman.)
3269
3270    zic -l no longer fails when compiled with -DTZDEFAULT=\"/etc/localtime\".
3271    This fixes a bug introduced in Release 2014f.
3272    (Problem reported by Leonardo Chiquitto.)
3273
3274
3275Release 2015d - 2015-04-24 08:09:46 -0700
3276
3277  Changes affecting future timestamps
3278
3279    Egypt will not observe DST in 2015 and will consider canceling it
3280    permanently.  For now, assume no DST indefinitely.
3281    (Thanks to Ahmed Nazmy and Tim Parenti.)
3282
3283  Changes affecting past timestamps
3284
3285    America/Whitehorse switched from UT -09 to -08 on 1967-05-28, not
3286    1966-07-01.  Also, Yukon's time zone history is documented better.
3287    (Thanks to Brian Inglis and Dennis Ferguson.)
3288
3289  Change affecting past and future time zone abbreviations
3290
3291    The abbreviations for Hawaii-Aleutian standard and daylight times
3292    have been changed from HAST/HADT to HST/HDT, as per US Government
3293    Printing Office style.  This affects only America/Adak since 1983,
3294    as America/Honolulu was already using the new style.
3295
3296  Changes affecting code
3297
3298   zic has some minor performance improvements.
3299
3300
3301Release 2015c - 2015-04-11 08:55:55 -0700
3302
3303  Changes affecting future timestamps
3304
3305    Egypt's spring-forward transition is at 24:00 on April's last Thursday,
3306    not 00:00 on April's last Friday.  2015's transition will therefore be on
3307    Thursday, April 30 at 24:00, not Friday, April 24 at 00:00.  Similar fixes
3308    apply to 2026, 2037, 2043, etc.  (Thanks to Steffen Thorsen.)
3309
3310  Changes affecting past timestamps
3311
3312    The following changes affect some pre-1991 Chile-related timestamps
3313    in America/Santiago, Antarctica/Palmer, and Pacific/Easter.
3314
3315      The 1910 transition was January 10, not January 1.
3316
3317      The 1918 transition was September 10, not September 1.
3318
3319      The UT -04 time observed from 1932 to 1942 is now considered to
3320      be standard time, not year-round DST.
3321
3322      Santiago observed DST (UT -03) from 1946-07-15 through
3323      1946-08-31, then reverted to standard time, then switched to -05
3324      on 1947-04-01.
3325
3326      Assume transitions before 1968 were at 00:00, since we have no data
3327      saying otherwise.
3328
3329      The spring 1988 transition was 1988-10-09, not 1988-10-02.
3330      The fall 1990 transition was 1990-03-11, not 1990-03-18.
3331
3332      Assume no UT offset change for Pacific/Easter on 1890-01-01,
3333      and omit all transitions on Pacific/Easter from 1942 through 1946
3334      since we have no data suggesting that they existed.
3335
3336    One more zone has been turned into a link, as it differed
3337    from an existing zone only for older timestamps.  As usual,
3338    this change affects UT offsets in pre-1970 timestamps only.
3339    The zone's old contents have been moved to the 'backzone' file.
3340    The affected zone is America/Montreal.
3341
3342  Changes affecting commentary
3343
3344    Mention the TZUpdater tool.
3345
3346    Mention "The Time Now".  (Thanks to Brandon Ramsey.)
3347
3348
3349Release 2015b - 2015-03-19 23:28:11 -0700
3350
3351  Changes affecting future timestamps
3352
3353    Mongolia will start observing DST again this year, from the last
3354    Saturday in March at 02:00 to the last Saturday in September at 00:00.
3355    (Thanks to Ganbold Tsagaankhuu.)
3356
3357    Palestine will start DST on March 28, not March 27.  Also,
3358    correct the fall 2014 transition from September 26 to October 24.
3359    Adjust future predictions accordingly.  (Thanks to Steffen Thorsen.)
3360
3361  Changes affecting past timestamps
3362
3363    The 1982 zone shift in Pacific/Easter has been corrected, fixing a 2015a
3364    regression.  (Thanks to Stuart Bishop for reporting the problem.)
3365
3366    Some more zones have been turned into links, when they differed
3367    from existing zones only for older timestamps.  As usual,
3368    these changes affect UT offsets in pre-1970 timestamps only.
3369    Their old contents have been moved to the 'backzone' file.
3370    The affected zones are: America/Antigua, America/Cayman,
3371    Pacific/Midway, and Pacific/Saipan.
3372
3373  Changes affecting time zone abbreviations
3374
3375    Correct the 1992-2010 DST abbreviation in Volgograd from "MSK" to "MSD".
3376    (Thanks to Hank W.)
3377
3378  Changes affecting code
3379
3380    Fix integer overflow bug in reference 'mktime' implementation.
3381    (Problem reported by Jörg Richter.)
3382
3383    Allow -Dtime_tz=time_t compilations, and allow -Dtime_tz=... libraries
3384    to be used in the same executable as standard-library time_t functions.
3385    (Problems reported by Bradley White.)
3386
3387  Changes affecting commentary
3388
3389    Cite the recent Mexican decree changing Quintana Roo's time zone.
3390    (Thanks to Carlos Raúl Perasso.)
3391
3392    Likewise for the recent Chilean decree.  (Thanks to Eduardo Romero Urra.)
3393
3394    Update info about Mars time.
3395
3396
3397Release 2015a - 2015-01-29 22:35:20 -0800
3398
3399  Changes affecting future timestamps
3400
3401    The Mexican state of Quintana Roo, represented by America/Cancun,
3402    will shift from Central Time with DST to Eastern Time without DST
3403    on 2015-02-01 at 02:00.  (Thanks to Steffen Thorsen and Gwillim Law.)
3404
3405    Chile will not change clocks in April or thereafter; its new standard time
3406    will be its old daylight saving time.  This affects America/Santiago,
3407    Pacific/Easter, and Antarctica/Palmer.  (Thanks to Juan Correa.)
3408
3409    New leap second 2015-06-30 23:59:60 UTC as per IERS Bulletin C 49.
3410    (Thanks to Tim Parenti.)
3411
3412  Changes affecting past timestamps
3413
3414    Iceland observed DST in 1919 and 1921, and its 1939 fallback
3415    transition was Oct. 29, not Nov. 29.  Remove incorrect data from
3416    Shanks about time in Iceland between 1837 and 1908.
3417
3418    Some more zones have been turned into links, when they differed
3419    from existing zones only for older timestamps.  As usual,
3420    these changes affect UT offsets in pre-1970 timestamps only.
3421    Their old contents have been moved to the 'backzone' file.
3422    The affected zones are: Asia/Aden, Asia/Bahrain, Asia/Kuwait,
3423    and Asia/Muscat.
3424
3425  Changes affecting code
3426
3427    tzalloc now scrubs time zone abbreviations compatibly with the way
3428    that tzset always has, by replacing invalid bytes with '_' and by
3429    shortening too-long abbreviations.
3430
3431    tzselect ports to POSIX awk implementations, no longer mishandles
3432    POSIX TZ settings when GNU awk is used, and reports POSIX TZ
3433    settings to the user.  (Thanks to Stefan Kuhn.)
3434
3435  Changes affecting build procedure
3436
3437    'make check' now checks for links to links in the data.
3438    One such link (for Africa/Asmera) has been fixed.
3439    (Thanks to Stephen Colebourne for pointing out the problem.)
3440
3441  Changes affecting commentary
3442
3443    The leapseconds file commentary now mentions the expiration date.
3444    (Problem reported by Martin Burnicki.)
3445
3446    Update Mexican Library of Congress URL.
3447
3448
3449Release 2014j - 2014-11-10 17:37:11 -0800
3450
3451  Changes affecting current and future timestamps
3452
3453    Turks & Caicos' switch from US eastern time to UT -04 year-round
3454    did not occur on 2014-11-02 at 02:00.  It's currently scheduled
3455    for 2015-11-01 at 02:00.  (Thanks to Chris Walton.)
3456
3457  Changes affecting past timestamps
3458
3459    Many pre-1989 timestamps have been corrected for Asia/Seoul and
3460    Asia/Pyongyang, based on sources for the Korean-language Wikipedia
3461    entry for time in Korea.  (Thanks to Sanghyuk Jung.)  Also, no
3462    longer guess that Pyongyang mimicked Seoul time after World War II,
3463    as this is politically implausible.
3464
3465    Some more zones have been turned into links, when they differed
3466    from existing zones only for older timestamps.  As usual,
3467    these changes affect UT offsets in pre-1970 timestamps only.
3468    Their old contents have been moved to the 'backzone' file.
3469    The affected zones are: Africa/Addis_Ababa, Africa/Asmara,
3470    Africa/Dar_es_Salaam, Africa/Djibouti, Africa/Kampala,
3471    Africa/Mogadishu, Indian/Antananarivo, Indian/Comoro, and
3472    Indian/Mayotte.
3473
3474  Changes affecting commentary
3475
3476    The commentary is less enthusiastic about Shanks as a source,
3477    and is more careful to distinguish UT from UTC.
3478
3479
3480Release 2014i - 2014-10-21 22:04:57 -0700
3481
3482  Changes affecting future timestamps
3483
3484    Pacific/Fiji will observe DST from 2014-11-02 02:00 to 2015-01-18 03:00.
3485    (Thanks to Ken Rylander for the heads-up.)  Guess that future
3486    years will use a similar pattern.
3487
3488    A new Zone Pacific/Bougainville, for the part of Papua New Guinea
3489    that plans to switch from UT +10 to +11 on 2014-12-28 at 02:00.
3490    (Thanks to Kiley Walbom for the heads-up.)
3491
3492  Changes affecting time zone abbreviations
3493
3494    Since Belarus is not changing its clocks even though Moscow is,
3495    the time zone abbreviation in Europe/Minsk is changing from FET
3496    to its more traditional value MSK on 2014-10-26 at 01:00.
3497    (Thanks to Alexander Bokovoy for the heads-up about Belarus.)
3498
3499    The new abbreviation IDT stands for the pre-1976 use of UT +08 in
3500    Indochina, to distinguish it better from ICT (+07).
3501
3502  Changes affecting past timestamps
3503
3504    Many timestamps have been corrected for Asia/Ho_Chi_Minh before 1976
3505    (thanks to Trần Ngọc Quân for an indirect pointer to Trần Tiến Bình's
3506    authoritative book).  Asia/Ho_Chi_Minh has been added to
3507    zone1970.tab, to give tzselect users in Vietnam two choices,
3508    since north and south Vietnam disagreed after our 1970 cutoff.
3509
3510    Asia/Phnom_Penh and Asia/Vientiane have been turned into links, as
3511    they differed from existing zones only for older timestamps.  As
3512    usual, these changes affect pre-1970 timestamps only.  Their old
3513    contents have been moved to the 'backzone' file.
3514
3515  Changes affecting code
3516
3517    The time-related library functions now set errno on failure, and
3518    some crashes in the new tzalloc-related library functions have
3519    been fixed.  (Thanks to Christos Zoulas for reporting most of
3520    these problems and for suggesting fixes.)
3521
3522    If USG_COMPAT is defined and the requested timestamp is standard time,
3523    the tz library's localtime and mktime functions now set the extern
3524    variable timezone to a value appropriate for that timestamp; and
3525    similarly for ALTZONE, daylight saving time, and the altzone variable.
3526    This change is a companion to the tzname change in 2014h, and is
3527    designed to make timezone and altzone more compatible with tzname.
3528
3529    The tz library's functions now set errno to EOVERFLOW if they fail
3530    because the result cannot be represented.  ctime and ctime_r now
3531    return NULL and set errno when a timestamp is out of range, rather
3532    than having undefined behavior.
3533
3534    Some bugs associated with the new 2014g functions have been fixed.
3535    This includes a bug that largely incapacitated the new functions
3536    time2posix_z and posix2time_z.  (Thanks to Christos Zoulas.)
3537    It also includes some uses of uninitialized variables after tzalloc.
3538    The new code uses the standard type 'ssize_t', which the Makefile
3539    now gives porting advice about.
3540
3541  Changes affecting commentary
3542
3543    Updated URLs for NRC Canada (thanks to Matt Johnson and Brian Inglis).
3544
3545
3546Release 2014h - 2014-09-25 18:59:03 -0700
3547
3548  Changes affecting past timestamps
3549
3550    America/Jamaica's 1974 spring-forward transition was Jan. 6, not Apr. 28.
3551
3552    Shanks says Asia/Novokuznetsk switched from LMT (not "NMT") on 1924-05-01,
3553    not 1920-01-06.  The old entry was based on a misinterpretation of Shanks.
3554
3555    Some more zones have been turned into links, when they differed
3556    from existing zones only for older timestamps.  As usual,
3557    these changes affect UT offsets in pre-1970 timestamps only.
3558    Their old contents have been moved to the 'backzone' file.
3559    The affected zones are: Africa/Blantyre, Africa/Bujumbura,
3560    Africa/Gaborone, Africa/Harare, Africa/Kigali, Africa/Lubumbashi,
3561    Africa/Lusaka, Africa/Maseru, and Africa/Mbabane.
3562
3563  Changes affecting code
3564
3565    zdump -V and -v now output gmtoff= values on all platforms,
3566    not merely on platforms defining TM_GMTOFF.
3567
3568    The tz library's localtime and mktime functions now set tzname to a value
3569    appropriate for the requested timestamp, and zdump now uses this
3570    on platforms not defining TM_ZONE, fixing a 2014g regression.
3571    (Thanks to Tim Parenti for reporting the problem.)
3572
3573    The tz library no longer sets tzname if localtime or mktime fails.
3574
3575    zdump -c no longer mishandles transitions near year boundaries.
3576    (Thanks to Tim Parenti for reporting the problem.)
3577
3578    An access to uninitialized data has been fixed.
3579    (Thanks to Jörg Richter for reporting the problem.)
3580
3581    When THREAD_SAFE is defined, the code ports to the C11 memory model.
3582    A memory leak has been fixed if ALL_STATE and THREAD_SAFE are defined
3583    and two threads race to initialize data used by gmtime-like functions.
3584    (Thanks to Andy Heninger for reporting the problems.)
3585
3586  Changes affecting build procedure
3587
3588    'make check' now checks better for properly sorted data.
3589
3590  Changes affecting documentation and commentary
3591
3592    zdump's gmtoff=N output is now documented, and its isdst=D output
3593    is now documented to possibly output D values other than 0 or 1.
3594
3595    zdump -c's treatment of years is now documented to use the
3596    Gregorian calendar and Universal Time without leap seconds,
3597    and its behavior at cutoff boundaries is now documented better.
3598    (Thanks to Arthur David Olson and Tim Parenti for reporting the problems.)
3599
3600    Programs are now documented to use the proleptic Gregorian calendar.
3601    (Thanks to Alan Barrett for the suggestion.)
3602
3603    Fractional-second GMT offsets have been documented for civil time
3604    in 19th-century Chennai, Jakarta, and New York.
3605
3606
3607Release 2014g - 2014-08-28 12:31:23 -0700
3608
3609  Changes affecting future timestamps
3610
3611    Turks & Caicos is switching from US eastern time to UT -04
3612    year-round, modeled as a switch on 2014-11-02 at 02:00.
3613    [As noted in 2014j, this switch was later delayed.]
3614
3615  Changes affecting past timestamps
3616
3617    Time in Russia or the USSR before 1926 or so has been corrected by
3618    a few seconds in the following zones: Asia/Irkutsk,
3619    Asia/Krasnoyarsk, Asia/Omsk, Asia/Samarkand, Asia/Tbilisi,
3620    Asia/Vladivostok, Asia/Yakutsk, Europe/Riga, Europe/Samara.  For
3621    Asia/Yekaterinburg the correction is a few minutes.  (Thanks to
3622    Vladimir Karpinsky.)
3623
3624    The Portuguese decree of 1911-05-26 took effect on 1912-01-01.
3625    This affects 1911 timestamps in Africa/Bissau, Africa/Luanda,
3626    Atlantic/Azores, and Atlantic/Madeira.  Also, Lisbon's pre-1912
3627    GMT offset was -0:36:45 (rounded from -0:36:44.68), not -0:36:32.
3628    (Thanks to Stephen Colebourne for pointing to the decree.)
3629
3630    Asia/Dhaka ended DST on 2009-12-31 at 24:00, not 23:59.
3631
3632    A new file 'backzone' contains data which may appeal to
3633    connoisseurs of old timestamps, although it is out of scope for
3634    the tz database, is often poorly sourced, and contains some data
3635    that is known to be incorrect.  The new file is not recommended
3636    for ordinary use and its entries are not installed by default.
3637    (Thanks to Lester Caine for the high-quality Jersey, Guernsey, and
3638    Isle of Man entries.)
3639
3640    Some more zones have been turned into links, when they differed
3641    from existing zones only for older timestamps.  As usual,
3642    these changes affect UT offsets in pre-1970 timestamps only.
3643    Their old contents have been moved to the 'backzone' file.
3644    The affected zones are: Africa/Bangui, Africa/Brazzaville,
3645    Africa/Douala, Africa/Kinshasa, Africa/Libreville, Africa/Luanda,
3646    Africa/Malabo, Africa/Niamey, and Africa/Porto-Novo.
3647
3648  Changes affecting code
3649
3650    Unless NETBSD_INSPIRED is defined to 0, the tz library now
3651    supplies functions for creating and using objects that represent
3652    timezones. The new functions are tzalloc, tzfree, localtime_rz,
3653    mktime_z, and (if STD_INSPIRED is also defined) posix2time_z and
3654    time2posix_z.  They are intended for performance: for example,
3655    localtime_rz (unlike localtime_r) is trivially thread-safe without
3656    locking.  (Thanks to Christos Zoulas for proposing NetBSD-inspired
3657    functions, and to Alan Barrett and Jonathan Lennox for helping to
3658    debug the change.)
3659
3660    zdump now builds with the tz library unless USE_LTZ is defined to 0,
3661    This lets zdump use tz features even if the system library lacks them.
3662    To build zdump with the system library, use 'make CFLAGS=-DUSE_LTZ=0
3663    TZDOBJS=zdump.o CHECK_TIME_T_ALTERNATIVES='.
3664
3665    zdump now uses localtime_rz if available, as it's significantly faster,
3666    and it can help zdump better diagnose invalid timezone names.
3667    Define HAVE_LOCALTIME_RZ to 0 to suppress this.  HAVE_LOCALTIME_RZ
3668    defaults to 1 if NETBSD_INSPIRED && USE_LTZ.  When localtime_rz is
3669    not available, zdump now uses localtime_r and tzset if available,
3670    as this is a bit cleaner and faster than plain localtime.  Compile
3671    with -DHAVE_LOCALTIME_R=0 and/or -DHAVE_TZSET=0 if your system
3672    lacks these two functions.
3673
3674    If THREAD_SAFE is defined to 1, the tz library is now thread-safe.
3675    Although not needed for tz's own applications, which are single-threaded,
3676    this supports POSIX better if the tz library is used in multithreaded apps.
3677
3678    Some crashes have been fixed when zdump or the tz library is given
3679    invalid or outlandish input.
3680
3681    The tz library no longer mishandles leap seconds on platforms with
3682    unsigned time_t in timezones that lack ordinary transitions after 1970.
3683
3684    The tz code now attempts to infer TM_GMTOFF and TM_ZONE if not
3685    already defined, to make it easier to configure on common platforms.
3686    Define NO_TM_GMTOFF and NO_TM_ZONE to suppress this.
3687
3688    Unless the new macro UNINIT_TRAP is defined to 1, the tz code now
3689    assumes that reading uninitialized memory yields garbage values
3690    but does not cause other problems such as traps.
3691
3692    If TM_GMTOFF is defined and UNINIT_TRAP is 0, mktime is now
3693    more likely to guess right for ambiguous timestamps near
3694    transitions where tm_isdst does not change.
3695
3696    If HAVE_STRFTIME_L is defined to 1, the tz library now defines
3697    strftime_l for compatibility with recent versions of POSIX.
3698    Only the C locale is supported, though.  HAVE_STRFTIME_L defaults
3699    to 1 on recent POSIX versions, and to 0 otherwise.
3700
3701    tzselect -c now uses a hybrid distance measure that works better
3702    in Africa.  (Thanks to Alan Barrett for noting the problem.)
3703
3704    The C source code now ports to NetBSD when GCC_DEBUG_FLAGS is used,
3705    or when time_tz is defined.
3706
3707    When HAVE_UTMPX_H is set the 'date' command now builds on systems
3708    whose <utmpx.h> file does not define WTMPX_FILE, and when setting
3709    the date it updates the wtmpx file if _PATH_WTMPX is defined.
3710    This affects GNU/Linux and similar systems.
3711
3712    For easier maintenance later, some C code has been simplified,
3713    some lint has been removed, and the code has been tweaked so that
3714    plain 'make' is more likely to work.
3715
3716    The C type 'bool' is now used for boolean values, instead of 'int'.
3717
3718    The long-obsolete LOCALE_HOME code has been removed.
3719
3720    The long-obsolete 'gtime' function has been removed.
3721
3722  Changes affecting build procedure
3723
3724    'zdump' no longer links in ialloc.o, as it's not needed.
3725
3726    'make check_time_t_alternatives' no longer assumes GNU diff.
3727
3728  Changes affecting distribution tarballs
3729
3730    The files checktab.awk and zoneinfo2tdf.pl are now distributed in
3731    the tzdata tarball instead of the tzcode tarball, since they help
3732    maintain the data.  The NEWS and Theory files are now also
3733    distributed in the tzdata tarball, as they're relevant for data.
3734    (Thanks to Alan Barrett for pointing this out.)  Also, the
3735    leapseconds.awk file is no longer distributed in the tzcode
3736    tarball, since it belongs in the tzdata tarball (where 2014f
3737    inadvertently also distributed it).
3738
3739  Changes affecting documentation and commentary
3740
3741    A new file CONTRIBUTING is distributed.  (Thanks to Tim Parenti for
3742    suggesting a CONTRIBUTING file, and to Tony Finch and Walter Harms
3743    for debugging it.)
3744
3745    The man pages have been updated to use function prototypes,
3746    to document thread-safe variants like localtime_r, and to document
3747    the NetBSD-inspired functions tzalloc, tzfree, localtime_rz, and
3748    mktime_z.
3749
3750    The fields in Link lines have been renamed to be more descriptive
3751    and more like the parameters of 'ln'.  LINK-FROM has become TARGET,
3752    and LINK-TO has become LINK-NAME.
3753
3754    tz-link.htm mentions the IETF's tzdist working group; Windows
3755    Runtime etc. (thanks to Matt Johnson); and HP-UX's tztab.
3756
3757    Some broken URLs have been fixed in the commentary.  (Thanks to
3758    Lester Caine.)
3759
3760    Commentary about Philippines DST has been updated, and commentary
3761    on pre-1970 time in India has been added.
3762
3763
3764Release 2014f - 2014-08-05 17:42:36 -0700
3765
3766  Changes affecting future timestamps
3767
3768    Russia will subtract an hour from most of its time zones on 2014-10-26
3769    at 02:00 local time.  (Thanks to Alexander Krivenyshev.)
3770    There are a few exceptions: Magadan Oblast (Asia/Magadan) and Zabaykalsky
3771    Krai are subtracting two hours; conversely, Chukotka Autonomous Okrug
3772    (Asia/Anadyr), Kamchatka Krai (Asia/Kamchatka), Kemerovo Oblast
3773    (Asia/Novokuznetsk), and the Samara Oblast and the Udmurt Republic
3774    (Europe/Samara) are not changing their clocks.  The changed zones are
3775    Europe/Kaliningrad, Europe/Moscow, Europe/Simferopol, Europe/Volgograd,
3776    Asia/Yekaterinburg, Asia/Omsk, Asia/Novosibirsk, Asia/Krasnoyarsk,
3777    Asia/Irkutsk, Asia/Yakutsk, Asia/Vladivostok, Asia/Khandyga,
3778    Asia/Sakhalin, and Asia/Ust-Nera; Asia/Magadan will have two hours
3779    subtracted; and Asia/Novokuznetsk's time zone abbreviation is affected,
3780    but not its UTC offset.  Two zones are added: Asia/Chita (split
3781    from Asia/Yakutsk, and also with two hours subtracted) and
3782    Asia/Srednekolymsk (split from Asia/Magadan, but with only one hour
3783    subtracted).  (Thanks to Tim Parenti for much of the above.)
3784
3785  Changes affecting time zone abbreviations
3786
3787    Australian eastern time zone abbreviations are now AEST/AEDT not EST,
3788    and similarly for the other Australian zones.  That is, for eastern
3789    standard and daylight saving time the abbreviations are AEST and AEDT
3790    instead of the former EST for both; similarly, ACST/ACDT, ACWST/ACWDT,
3791    and AWST/AWDT are now used instead of the former CST, CWST, and WST.
3792    This change does not affect UT offsets, only time zone abbreviations.
3793    (Thanks to Rich Tibbett and many others.)
3794
3795    Asia/Novokuznetsk shifts from NOVT to KRAT (remaining on UT +07)
3796    effective 2014-10-26 at 02:00 local time.
3797
3798    The time zone abbreviation for Xinjiang Time (observed in Ürümqi)
3799    has been changed from URUT to XJT.  (Thanks to Luther Ma.)
3800
3801    Prefer MSK/MSD for Moscow time in Russia, even in other cities.
3802    Similarly, prefer EET/EEST for eastern European time in Russia.
3803
3804    Change time zone abbreviations in (western) Samoa to use "ST" and
3805    "DT" suffixes, as this is more likely to match common practice.
3806    Prefix "W" to (western) Samoa time when its standard-time offset
3807    disagrees with that of American Samoa.
3808
3809    America/Metlakatla now uses PST, not MeST, to abbreviate its time zone.
3810
3811    Time zone abbreviations have been updated for Japan's two time
3812    zones used 1896-1937.  JWST now stands for Western Standard
3813    Time, and JCST for Central Standard Time (formerly this was CJT).
3814    These abbreviations are now used for time in Korea, Taiwan,
3815    and Sakhalin while controlled by Japan.
3816
3817  Changes affecting past timestamps
3818
3819    China's five zones have been simplified to two, since the post-1970
3820    differences in the other three seem to have been imaginary.  The
3821    zones Asia/Harbin, Asia/Chongqing, and Asia/Kashgar have been
3822    removed; backwards-compatibility links still work, albeit with
3823    different behaviors for timestamps before May 1980.  Asia/Urumqi's
3824    1980 transition to UT +08 has been removed, so that it is now at
3825    +06 and not +08.  (Thanks to Luther Ma and to Alois Treindl;
3826    Treindl sent helpful translations of two papers by Guo Qingsheng.)
3827
3828    Some zones have been turned into links, when they differed from existing
3829    zones only for older UT offsets where data entries were likely invented.
3830    These changes affect UT offsets in pre-1970 timestamps only.  This is
3831    similar to the change in release 2013e, except this time for western
3832    Africa.  The affected zones are: Africa/Bamako, Africa/Banjul,
3833    Africa/Conakry, Africa/Dakar, Africa/Freetown, Africa/Lome,
3834    Africa/Nouakchott, Africa/Ouagadougou, Africa/Sao_Tome, and
3835    Atlantic/St_Helena.  This also affects the backwards-compatibility
3836    link Africa/Timbuktu.  (Thanks to Alan Barrett, Stephen Colebourne,
3837    Tim Parenti, and David Patte for reporting problems in earlier
3838    versions of this change.)
3839
3840    Asia/Shanghai's pre-standard-time UT offset has been changed from
3841    8:05:57 to 8:05:43, the location of Xujiahui Observatory.  Its
3842    transition to standard time has been changed from 1928 to 1901.
3843
3844    Asia/Taipei switched to JWST on 1896-01-01, then to JST on 1937-10-01,
3845    then to CST on 1945-09-21 at 01:00, and did not observe DST in 1945.
3846    In 1946 it observed DST from 05-15 through 09-30; in 1947
3847    from 04-15 through 10-31; and in 1979 from 07-01 through 09-30.
3848    (Thanks to Yu-Cheng Chuang.)
3849
3850    Asia/Riyadh's transition to standard time is now 1947-03-14, not 1950.
3851
3852    Europe/Helsinki's 1942 fall-back transition was 10-04 at 01:00, not
3853    10-03 at 00:00.  (Thanks to Konstantin Hyppönen.)
3854
3855    Pacific/Pago_Pago has been changed from UT -11:30 to -11 for the
3856    period from 1911 to 1950.
3857
3858    Pacific/Chatham has been changed to New Zealand standard time plus
3859    45 minutes for the period before 1957, reflecting a 1956 remark in
3860    the New Zealand parliament.
3861
3862    Europe/Budapest has several pre-1946 corrections: in 1918 the transition
3863    out of DST was on 09-16, not 09-29; in 1919 it was on 11-24, not 09-15; in
3864    1945 it was on 11-01, not 11-03; in 1941 the transition to DST was 04-08
3865    not 04-06 at 02:00; and there was no DST in 1920.
3866
3867    Africa/Accra is now assumed to have observed DST from 1920 through 1935.
3868
3869    Time in Russia before 1927 or so has been corrected by a few seconds in
3870    the following zones: Europe/Moscow, Asia/Irkutsk, Asia/Tbilisi,
3871    Asia/Tashkent, Asia/Vladivostok, Asia/Yekaterinburg, Europe/Helsinki, and
3872    Europe/Riga.  Also, Moscow's location has been changed to its Kilometer 0
3873    point.  (Thanks to Vladimir Karpinsky for the Moscow changes.)
3874
3875  Changes affecting data format
3876
3877    A new file 'zone1970.tab' supersedes 'zone.tab' in the installed data.
3878    The new file's extended format allows multiple country codes per zone.
3879    The older file is still installed but is deprecated; its format is
3880    not changing and it will still be distributed for a while, but new
3881    applications should use the new file.
3882
3883    The new file format simplifies maintenance of obscure locations.
3884    To test this, it adds coverage for the Crozet Islands and the
3885    Scattered Islands.  (Thanks to Tobias Conradi and Antoine Leca.)
3886
3887    The file 'iso3166.tab' is planned to switch from ASCII to UTF-8.
3888    It is still ASCII now, but commentary about the switch has been added.
3889    The new file 'zone1970.tab' already uses UTF-8.
3890
3891  Changes affecting code
3892
3893    'localtime', 'mktime', etc. now use much less stack space if ALL_STATE
3894    is defined.  (Thanks to Elliott Hughes for reporting the problem.)
3895
3896    'zic' no longer mishandles input when ignoring case in locales that
3897    are not compatible with English, e.g., unibyte Turkish locales when
3898    compiled with HAVE_GETTEXT.
3899
3900    Error diagnostics of 'zic' and 'yearistype' have been reworded so that
3901    they no longer use ASCII '-' as if it were a dash.
3902
3903    'zic' now rejects output file names that contain '.' or '..' components.
3904    (Thanks to Tim Parenti for reporting the problem.)
3905
3906    'zic -v' now warns about output file names that do not follow
3907    POSIX rules, or that contain a digit or '.'.  (Thanks to Arthur
3908    David Olson for starting the ball rolling on this.)
3909
3910    Some lint has been removed when using GCC_DEBUG_FLAGS with GCC 4.9.0.
3911
3912  Changes affecting build procedure
3913
3914    'zic' no longer links in localtime.o and asctime.o, as they're not needed.
3915    (Thanks to John Cochran.)
3916
3917  Changes affecting documentation and commentary
3918
3919    The 'Theory' file documents legacy names, the longstanding
3920    exceptions to the POSIX-inspired file name rules.
3921
3922    The 'zic' documentation clarifies the role of time types when
3923    interpreting dates.  (Thanks to Arthur David Olson.)
3924
3925    Documentation and commentary now prefer UTF-8 to US-ASCII,
3926    allowing the use of proper accents in foreign words and names.
3927    Code and data have not changed because of this.  (Thanks to
3928    Garrett Wollman, Ian Abbott, and Guy Harris for helping to debug
3929    this.)
3930
3931    Non-HTML documentation and commentary now use plain-text URLs instead of
3932    HTML insertions, and are more consistent about bracketing URLs when they
3933    are not already surrounded by white space.  (Thanks to suggestions by
3934    Steffen Nurpmeso.)
3935
3936    There is new commentary about Xujiahui Observatory, the five time-zone
3937    project in China from 1918 to 1949, timekeeping in Japanese-occupied
3938    Shanghai, and Tibet Time in the 1950s.  The sharp-eyed can spot the
3939    warlord Jin Shuren in the data.
3940
3941    Commentary about the coverage of each Russian zone has been standardized.
3942    (Thanks to Tim Parenti.)
3943
3944    There is new commentary about contemporary timekeeping in Ethiopia.
3945
3946    Obsolete comments about a 2007 proposal for DST in Kuwait has been removed.
3947
3948    There is new commentary about time in Poland in 1919.
3949
3950    Proper credit has been given to DST inventor George Vernon Hudson.
3951
3952    Commentary about time in Metlakatla, AK and Resolute, NU has been
3953    improved, with a new source for the former.
3954
3955    In zone.tab, Pacific/Easter no longer mentions Salas y Gómez, as it
3956    is uninhabited.
3957
3958    Commentary about permanent Antarctic bases has been updated.
3959
3960    Several typos have been corrected.  (Thanks to Tim Parenti for
3961    contributing some of these fixes.)
3962
3963    tz-link.htm now mentions the JavaScript libraries Moment Timezone,
3964    TimezoneJS.Date, Walltime-js, and Timezone.  (Thanks to a heads-up
3965    from Matt Johnson.)  Also, it mentions the Go 'latlong' package.
3966    (Thanks to a heads-up from Dirkjan Ochtman.)
3967
3968    The files usno1988, usno1989, usno1989a, usno1995, usno1997, and usno1998
3969    have been removed.  These obsolescent US Naval Observatory entries were no
3970    longer helpful for maintenance.  (Thanks to Tim Parenti for the suggestion.)
3971
3972
3973Release 2014e - 2014-06-12 21:53:52 -0700
3974
3975  Changes affecting near-future timestamps
3976
3977    Egypt's 2014 Ramadan-based transitions are June 26 and July 31 at 24:00.
3978    (Thanks to Imed Chihi.)  Guess that from 2015 on Egypt will temporarily
3979    switch to standard time at 24:00 the last Thursday before Ramadan, and
3980    back to DST at 00:00 the first Friday after Ramadan.
3981
3982    Similarly, Morocco's are June 28 at 03:00 and August 2 at 02:00.  (Thanks
3983    to Milamber Space Network.)  Guess that from 2015 on Morocco will
3984    temporarily switch to standard time at 03:00 the last Saturday before
3985    Ramadan, and back to DST at 02:00 the first Saturday after Ramadan.
3986
3987  Changes affecting past timestamps
3988
3989    The abbreviation "MSM" (Moscow Midsummer Time) is now used instead of
3990    "MSD" for Moscow's double daylight time in summer 1921.  Also, a typo
3991    "VLASST" has been repaired to be "VLAST" for Vladivostok summer time
3992    in 1991.  (Thanks to Hank W. for reporting the problems.)
3993
3994  Changes affecting commentary
3995
3996    tz-link.htm now cites RFC 7265 for jCal, mentions PTP and the
3997    draft CalDAV extension, updates URLs for TSP, TZInfo, IATA, and
3998    removes stale pointers to World Time Explorer and WORLDTIME.
3999
4000
4001Release 2014d - 2014-05-27 21:34:40 -0700
4002
4003  Changes affecting code
4004
4005    zic no longer generates files containing timestamps before the Big Bang.
4006    This works around GNOME glib bug 878
4007    <https://gitlab.gnome.org/GNOME/glib/issues/878>
4008    (Thanks to Leonardo Chiquitto for reporting the bug, and to
4009    Arthur David Olson and James Cloos for suggesting improvements to the fix.)
4010
4011  Changes affecting documentation
4012
4013    tz-link.htm now mentions GNOME.
4014
4015
4016Release 2014c - 2014-05-13 07:44:13 -0700
4017
4018  Changes affecting near-future timestamps
4019
4020    Egypt observes DST starting 2014-05-15 at 24:00.
4021    (Thanks to Ahmad El-Dardiry and Gunther Vermier.)
4022    Details have not been announced, except that DST will not be observed
4023    during Ramadan.  Guess that DST will stop during the same Ramadan dates as
4024    Morocco, and that Egypt's future spring and fall transitions will be the
4025    same as 2010 when it last observed DST, namely April's last Friday at
4026    00:00 to September's last Thursday at 23:00 standard time.  Also, guess
4027    that Ramadan transitions will be at 00:00 standard time.
4028
4029  Changes affecting code
4030
4031    zic now generates transitions for minimum time values, eliminating guesswork
4032    when handling low-valued timestamps.  (Thanks to Arthur David Olson.)
4033
4034    Port to Cygwin sans glibc.  (Thanks to Arthur David Olson.)
4035
4036  Changes affecting commentary and documentation
4037
4038    Remove now-confusing comment about Jordan.  (Thanks to Oleksii Nochovnyi.)
4039
4040
4041Release 2014b - 2014-03-24 21:28:50 -0700
4042
4043  Changes affecting near-future timestamps
4044
4045    Crimea switches to Moscow time on 2014-03-30 at 02:00 local time.
4046    (Thanks to Alexander Krivenyshev.)  Move its zone.tab entry from UA to RU.
4047
4048    New entry for Troll station, Antarctica.  (Thanks to Paul-Inge Flakstad and
4049    Bengt-Inge Larsson.)  This is currently an approximation; a better version
4050    will require the zic and localtime fixes mentioned below, and the plan is
4051    to wait for a while until at least the zic fixes propagate.
4052
4053  Changes affecting code
4054
4055    'zic' and 'localtime' no longer reject locations needing four transitions
4056    per year for the foreseeable future.  (Thanks to Andrew Main (Zefram).)
4057    Also, 'zic' avoids some unlikely failures due to integer overflow.
4058
4059  Changes affecting build procedure
4060
4061    'make check' now detects Rule lines defined but never used.
4062    The NZAQ rules, an instance of this problem, have been removed.
4063
4064  Changes affecting commentary and documentation
4065
4066    Fix Tuesday/Thursday typo in description of time in Israel.
4067    (Thanks to Bert Katz via Pavel Kharitonov and Mike Frysinger.)
4068
4069    Microsoft Windows 8.1 doesn't support tz database names.  (Thanks
4070    to Donald MacQueen.)  Instead, the Microsoft Windows Store app
4071    library supports them.
4072
4073    Add comments about Johnston Island time in the 1960s.
4074    (Thanks to Lyle McElhaney.)
4075
4076    Morocco's 2014 DST start will be as predicted.
4077    (Thanks to Sebastien Willemijns.)
4078
4079
4080Release 2014a - 2014-03-07 23:30:29 -0800
4081
4082  Changes affecting near-future timestamps
4083
4084    Turkey begins DST on 2014-03-31, not 03-30.  (Thanks to Faruk Pasin for
4085    the heads-up, and to Tim Parenti for simplifying the update.)
4086
4087  Changes affecting past timestamps
4088
4089    Fiji ended DST on 2014-01-19 at 02:00, not the previously scheduled 03:00.
4090    (Thanks to Steffen Thorsen.)
4091
4092    Ukraine switched from Moscow to Eastern European time on 1990-07-01
4093    (not 1992-01-01), and observed DST during the entire next winter.
4094    (Thanks to Vladimir in Moscow via Alois Treindl.)
4095
4096    In 1988 Israel observed DST from 04-10 to 09-04, not 04-09 to 09-03.
4097    (Thanks to Avigdor Finkelstein.)
4098
4099  Changes affecting code
4100
4101    A uninitialized-storage bug in 'localtime' has been fixed.
4102    (Thanks to Logan Chien.)
4103
4104  Changes affecting the build procedure
4105
4106    The settings for 'make check_web' now default to Ubuntu 13.10.
4107
4108  Changes affecting commentary and documentation
4109
4110    The boundary of the US Pacific time zone is given more accurately.
4111    (Thanks to Alan Mintz.)
4112
4113    Chile's 2014 DST will be as predicted.  (Thanks to José Miguel Garrido.)
4114
4115    Paraguay's 2014 DST will be as predicted.  (Thanks to Carlos Raúl Perasso.)
4116
4117    Better descriptions of countries with same time zone history as
4118    Trinidad and Tobago since 1970.  (Thanks to Alan Barrett for suggestion.)
4119
4120    Several changes affect tz-link.htm, the main web page.
4121
4122      Mention Time.is (thanks to Even Scharning) and WX-now (thanks to
4123      David Braverman).
4124
4125      Mention xCal (Internet RFC 6321) and jCal.
4126
4127      Microsoft has some support for tz database names.
4128
4129      CLDR data formats include both XML and JSON.
4130
4131      Mention Maggiolo's map of solar vs standard time.
4132      (Thanks to Arthur David Olson.)
4133
4134      Mention TZ4Net.  (Thanks to Matt Johnson.)
4135
4136      Mention the timezone-olson Haskell package.
4137
4138      Mention zeitverschiebung.net.  (Thanks to Martin Jäger.)
4139
4140      Remove moribund links to daylight-savings-time.info and to
4141      Simple Timer + Clocks.
4142
4143      Update two links.  (Thanks to Oscar van Vlijmen.)
4144
4145      Fix some formatting glitches, e.g., remove random newlines from
4146      abbr elements' title attributes.
4147
4148
4149Release 2013i - 2013-12-17 07:25:23 -0800
4150
4151  Changes affecting near-future timestamps:
4152
4153    Jordan switches back to standard time at 00:00 on December 20, 2013.
4154    The 2006-2011 transition schedule is planned to resume in 2014.
4155    (Thanks to Steffen Thorsen.)
4156
4157  Changes affecting past timestamps:
4158
4159    In 2004, Cuba began DST on March 28, not April 4.
4160    (Thanks to Steffen Thorsen.)
4161
4162  Changes affecting code
4163
4164    The compile-time flag NOSOLAR has been removed, as nowadays the
4165    benefit of slightly shrinking runtime table size is outweighed by the
4166    cost of disallowing potential future updates that exceed old limits.
4167
4168  Changes affecting documentation and commentary
4169
4170    The files solar87, solar88, and solar89 are no longer distributed.
4171    They were a negative experiment - that is, a demonstration that
4172    tz data can represent solar time only with some difficulty and error.
4173    Their presence in the distribution caused confusion, as Riyadh
4174    civil time was generally not solar time in those years.
4175
4176    tz-link.htm now mentions Noda Time.  (Thanks to Matt Johnson.)
4177
4178
4179Release 2013h - 2013-10-25 15:32:32 -0700
4180
4181  Changes affecting current and future timestamps:
4182
4183    Libya has switched its UT offset back to +02 without DST, instead
4184    of +01 with DST.  (Thanks to Even Scharning.)
4185
4186    Western Sahara (Africa/El_Aaiun) uses Morocco's DST rules.
4187    (Thanks to Gwillim Law.)
4188
4189  Changes affecting future timestamps:
4190
4191    Acre and (we guess) western Amazonas will switch from UT -04 to -05
4192    on 2013-11-10.  This affects America/Rio_Branco and America/Eirunepe.
4193    (Thanks to Steffen Thorsen.)
4194
4195    Add entries for DST transitions in Morocco in the year 2038.
4196    This avoids some year-2038 glitches introduced in 2013g.
4197    (Thanks to Yoshito Umaoka for reporting the problem.)
4198
4199  Changes affecting API
4200
4201    The 'tzselect' command no longer requires the 'select' command,
4202    and should now work with /bin/sh on more platforms.  It also works
4203    around a bug in BusyBox awk before version 1.21.0.  (Thanks to
4204    Patrick 'P. J.' McDermott and Alan Barrett.)
4205
4206  Changes affecting code
4207
4208    Fix localtime overflow bugs with 32-bit unsigned time_t.
4209
4210    zdump no longer assumes sscanf returns maximal values on overflow.
4211
4212  Changes affecting the build procedure
4213
4214    The builder can specify which programs to use, if any, instead of
4215    'ar' and 'ranlib', and libtz.a is now built locally before being
4216    installed.  (Thanks to Michael Forney.)
4217
4218    A dependency typo in the 'zdump' rule has been fixed.
4219    (Thanks to Andrew Paprocki.)
4220
4221    The Makefile has been simplified by assuming that 'mkdir -p' and 'cp -f'
4222    work as specified by POSIX.2-1992 or later; this is portable nowadays.
4223
4224    'make clean' no longer removes 'leapseconds', since it's
4225    host-independent and is part of the distribution.
4226
4227    The unused makefile macros TZCSRCS, TZDSRCS, DATESRCS have been removed.
4228
4229  Changes affecting documentation and commentary
4230
4231    tz-link.htm now mentions TC TIMEZONE's draft time zone service protocol
4232    (thanks to Mike Douglass) and TimezoneJS.Date (thanks to Jim Fehrle).
4233
4234    Update URLs in tz-link page.  Add URLs for Microsoft Windows, since
4235    8.1 introduces tz support.  Remove URLs for Tru64 and UnixWare (no
4236    longer maintained) and for old advisories.  SOFA now does C.
4237
4238Release 2013g - 2013-09-30 21:08:26 -0700
4239
4240  Changes affecting current and near-future timestamps
4241
4242    Morocco now observes DST from the last Sunday in March to the last
4243    Sunday in October, not April to September respectively.  (Thanks
4244    to Steffen Thorsen.)
4245
4246  Changes affecting 'zic'
4247
4248    'zic' now runs on platforms that lack both hard links and symlinks.
4249    (Thanks to Theo Veenker for reporting the problem, for MinGW.)
4250    Also, fix some bugs on platforms that lack hard links but have symlinks.
4251
4252    'zic -v' again warns that Asia/Tehran has no POSIX environment variable
4253    to predict the far future, fixing a bug introduced in 2013e.
4254
4255  Changes affecting the build procedure
4256
4257    The 'leapseconds' file is again put into the tzdata tarball.
4258    Also, 'leapseconds.awk', so tzdata is self-contained.  (Thanks to
4259    Matt Burgess and Ian Abbott.)  The timestamps of these and other
4260    dependent files in tarballs are adjusted more consistently.
4261
4262  Changes affecting documentation and commentary
4263
4264    The README file is now part of the data tarball as well as the code.
4265    It now states that files are public domain unless otherwise specified.
4266    (Thanks to Andrew Main (Zefram) for asking for clarifications.)
4267    Its details about the 1989 release moved to a place of honor near
4268    the end of NEWS.
4269
4270
4271Release 2013f - 2013-09-24 23:37:36 -0700
4272
4273  Changes affecting near-future timestamps
4274
4275    Tocantins will very likely not observe DST starting this spring.
4276    (Thanks to Steffen Thorsen.)
4277
4278    Jordan will likely stay at UT +03 indefinitely, and will not fall
4279    back this fall.
4280
4281    Palestine will fall back at 00:00, not 01:00.  (Thanks to Steffen Thorsen.)
4282
4283  Changes affecting API
4284
4285    The types of the global variables 'timezone' and 'altzone' (if present)
4286    have been changed back to 'long'.  This is required for 'timezone'
4287    by POSIX, and for 'altzone' by common practice, e.g., Solaris 11.
4288    These variables were originally 'long' in the tz code, but were
4289    mistakenly changed to 'time_t' in 1987; nobody reported the
4290    incompatibility until now.  The difference matters on x32, where
4291    'long' is 32 bits and 'time_t' is 64.  (Thanks to Elliott Hughes.)
4292
4293  Changes affecting the build procedure
4294
4295    Avoid long strings in leapseconds.awk to work around a mawk bug.
4296    (Thanks to Cyril Baurand.)
4297
4298  Changes affecting documentation and commentary
4299
4300    New file 'NEWS' that contains release notes like this one.
4301
4302    Paraguay's law does not specify DST transition time; 00:00 is customary.
4303    (Thanks to Waldemar Villamayor-Venialbo.)
4304
4305    Minor capitalization fixes.
4306
4307  Changes affecting version-control only
4308
4309    The experimental GitHub repository now contains annotated and
4310    signed tags for recent releases, e.g., '2013e' for Release 2013e.
4311    Releases are tagged starting with 2012e; earlier releases were
4312    done differently, and tags would either not have a simple name or
4313    not exactly match what was released.
4314
4315    'make set-timestamps' is now simpler and a bit more portable.
4316
4317
4318Release 2013e - 2013-09-19 23:50:04 -0700
4319
4320  Changes affecting near-future timestamps
4321
4322    This year Fiji will start DST on October 27, not October 20.
4323    (Thanks to David Wheeler for the heads-up.)  For now, guess that
4324    Fiji will continue to spring forward the Sunday before the fourth
4325    Monday in October.
4326
4327  Changes affecting current and future time zone abbreviations
4328
4329    Use WIB/WITA/WIT rather than WIT/CIT/EIT for alphabetic Indonesian
4330    time zone abbreviations since 1932.  (Thanks to George Ziegler,
4331    Priyadi Iman Nurcahyo, Zakaria, Jason Grimes, Martin Pitt, and
4332    Benny Lin.)  This affects Asia/Dili, Asia/Jakarta, Asia/Jayapura,
4333    Asia/Makassar, and Asia/Pontianak.
4334
4335    Use ART (UT -03, standard time), rather than WARST (also -03, but
4336    daylight saving time) for San Luis, Argentina since 2009.
4337
4338  Changes affecting Godthåb timestamps after 2037 if version mismatch
4339
4340    Allow POSIX-like TZ strings where the transition time's hour can
4341    range from -167 through 167, instead of the POSIX-required 0
4342    through 24.  E.g., TZ='FJT-12FJST,M10.3.1/146,M1.3.4/75' for the
4343    new Fiji rules.  This is a more compact way to represent
4344    far-future timestamps for America/Godthab, America/Santiago,
4345    Antarctica/Palmer, Asia/Gaza, Asia/Hebron, Asia/Jerusalem,
4346    Pacific/Easter, and Pacific/Fiji.  Other zones are unaffected by
4347    this change.  (Derived from a suggestion by Arthur David Olson.)
4348
4349    Allow POSIX-like TZ strings where daylight saving time is in
4350    effect all year.  E.g., TZ='WART4WARST,J1/0,J365/25' for Western
4351    Argentina Summer Time all year.  This supports a more compact way
4352    to represent the 2013d data for America/Argentina/San_Luis.
4353    Because of the change for San Luis noted above this change does not
4354    affect the current data.  (Thanks to Andrew Main (Zefram) for
4355    suggestions that improved this change.)
4356
4357    Where these two TZ changes take effect, there is a minor extension
4358    to the tz file format in that it allows new values for the
4359    embedded TZ-format string, and the tz file format version number
4360    has therefore been increased from 2 to 3 as a precaution.
4361    Version-2-based client code should continue to work as before for
4362    all timestamps before 2038.  Existing version-2-based client code
4363    (tzcode, GNU/Linux, Solaris) has been tested on version-3-format
4364    files, and typically works in practice even for timestamps after
4365    2037; the only known exception is America/Godthab.
4366
4367  Changes affecting timestamps before 1970
4368
4369    Pacific/Johnston is now a link to Pacific/Honolulu.  This corrects
4370    some errors before 1947.
4371
4372    Some zones have been turned into links, when they differ from existing
4373    zones only in older data entries that were likely invented or that
4374    differ only in LMT or transitions from LMT.  These changes affect
4375    only timestamps before 1943.  The affected zones are:
4376    Africa/Juba, America/Anguilla, America/Aruba, America/Dominica,
4377    America/Grenada, America/Guadeloupe, America/Marigot,
4378    America/Montserrat, America/St_Barthelemy, America/St_Kitts,
4379    America/St_Lucia, America/St_Thomas, America/St_Vincent,
4380    America/Tortola, and Europe/Vaduz.  (Thanks to Alois Treindl for
4381    confirming that the old Europe/Vaduz zone was wrong and the new
4382    link is better for WWII-era times.)
4383
4384    Change Kingston Mean Time from -5:07:12 to -5:07:11.  This affects
4385    America/Cayman, America/Jamaica and America/Grand_Turk timestamps
4386    from 1890 to 1912.
4387
4388    Change the UT offset of Bern Mean Time from 0:29:44 to 0:29:46.
4389    This affects Europe/Zurich timestamps from 1853 to 1894.  (Thanks
4390    to Alois Treindl.)
4391
4392    Change the date of the circa-1850 Zurich transition from 1849-09-12
4393    to 1853-07-16, overriding Shanks with data from Messerli about
4394    postal and telegraph time in Switzerland.
4395
4396  Changes affecting time zone abbreviations before 1970
4397
4398    For Asia/Jakarta, use BMT (not JMT) for mean time from 1923 to 1932,
4399    as Jakarta was called Batavia back then.
4400
4401  Changes affecting API
4402
4403    The 'zic' command now outputs a dummy transition when far-future
4404    data can't be summarized using a TZ string, and uses a 402-year
4405    window rather than a 400-year window.  For the current data, this
4406    affects only the Asia/Tehran file.  It does not affect any of the
4407    timestamps that this file represents, so zdump outputs the same
4408    information as before.  (Thanks to Andrew Main (Zefram).)
4409
4410    The 'date' command has a new '-r' option, which lets you specify
4411    the integer time to display, a la FreeBSD.
4412
4413    The 'tzselect' command has two new options '-c' and '-n', which lets you
4414    select a zone based on latitude and longitude.
4415
4416    The 'zic' command's '-v' option now warns about constructs that
4417    require the new version-3 binary file format.  (Thanks to Arthur
4418    David Olson for the suggestion.)
4419
4420    Support for floating-point time_t has been removed.
4421    It was always dicey, and POSIX no longer requires it.
4422    (Thanks to Eric Blake for suggesting to the POSIX committee to
4423    remove it, and thanks to Alan Barrett, Clive D.W. Feather, Andy
4424    Heninger, Arthur David Olson, and Alois Treindl, for reporting
4425    bugs and elucidating some of the corners of the old floating-point
4426    implementation.)
4427
4428    The signatures of 'offtime', 'timeoff', and 'gtime' have been
4429    changed back to the old practice of using 'long' to represent UT
4430    offsets.  This had been inadvertently and mistakenly changed to
4431    'int_fast32_t'.  (Thanks to Christos Zoulas.)
4432
4433    The code avoids undefined behavior on integer overflow in some
4434    more places, including gmtime, localtime, mktime and zdump.
4435
4436  Changes affecting the zdump utility
4437
4438    zdump now outputs "UT" when referring to Universal Time, not "UTC".
4439    "UTC" does not make sense for timestamps that predate the introduction
4440    of UTC, whereas "UT", a more generic term, does.  (Thanks to Steve Allen
4441    for clarifying UT vs UTC.)
4442
4443  Data changes affecting behavior of tzselect and similar programs
4444
4445    Country code BQ is now called the more common name "Caribbean Netherlands"
4446    rather than the more official "Bonaire, St Eustatius & Saba".
4447
4448    Remove from zone.tab the names America/Montreal, America/Shiprock,
4449    and Antarctica/South_Pole, as they are equivalent to existing
4450    same-country-code zones for post-1970 timestamps.  The data entries for
4451    these names are unchanged, so the names continue to work as before.
4452
4453  Changes affecting code internals
4454
4455    zic -c now runs way faster on 64-bit hosts when given large numbers.
4456
4457    zic now uses vfprintf to avoid allocating and freeing some memory.
4458
4459    tzselect now computes the list of continents from the data,
4460    rather than have it hard-coded.
4461
4462    Minor changes pacify GCC 4.7.3 and GCC 4.8.1.
4463
4464  Changes affecting the build procedure
4465
4466    The 'leapseconds' file is now generated automatically from a
4467    new file 'leap-seconds.list', which is a copy of
4468    <ftp://ftp.nist.gov/pub/time/leap-seconds.list>
4469    A new source file 'leapseconds.awk' implements this.
4470    The goal is simplification of the future maintenance of 'leapseconds'.
4471
4472    When building the 'posix' or 'right' subdirectories, if the
4473    subdirectory would be a copy of the default subdirectory, it is
4474    now made a symbolic link if that is supported.  This saves about
4475    2 MB of file system space.
4476
4477    The links America/Shiprock and Antarctica/South_Pole have been
4478    moved to the 'backward' file.  This affects only nondefault builds
4479    that omit 'backward'.
4480
4481  Changes affecting version-control only
4482
4483    .gitignore now ignores 'date'.
4484
4485  Changes affecting documentation and commentary
4486
4487    Changes to the 'tzfile' man page
4488
4489      It now mentions that the binary file format may be extended in
4490      future versions by appending data.
4491
4492      It now refers to the 'zdump' and 'zic' man pages.
4493
4494    Changes to the 'zic' man page
4495
4496      It lists conditions that elicit a warning with '-v'.
4497
4498      It says that the behavior is unspecified when duplicate names
4499      are given, or if the source of one link is the target of another.
4500
4501      Its examples are updated to match the latest data.
4502
4503      The definition of white space has been clarified slightly.
4504      (Thanks to Michael Deckers.)
4505
4506    Changes to the 'Theory' file
4507
4508      There is a new section about the accuracy of the tz database,
4509      describing the many ways that errors can creep in, and
4510      explaining why so many of the pre-1970 timestamps are wrong or
4511      misleading (thanks to Steve Allen, Lester Caine, and Garrett
4512      Wollman for discussions that contributed to this).
4513
4514      The 'Theory' file describes LMT better (this follows a
4515      suggestion by Guy Harris).
4516
4517      It refers to the 2013 edition of POSIX rather than the 2004 edition.
4518
4519      It's mentioned that excluding 'backward' should not affect the
4520      other data, and it suggests at least one zone.tab name per
4521      inhabited country (thanks to Stephen Colebourne).
4522
4523      Some longstanding restrictions on names are documented, e.g.,
4524      'America/New_York' precludes 'America/New_York/Bronx'.
4525
4526      It gives more reasons for the 1970 cutoff.
4527
4528      It now mentions which time_t variants are supported, such as
4529      signed integer time_t.  (Thanks to Paul Goyette for reporting
4530      typos in an experimental version of this change.)
4531
4532      (Thanks to Philip Newton for correcting typos in these changes.)
4533
4534    Documentation and commentary is more careful to distinguish UT in
4535    general from UTC in particular.  (Thanks to Steve Allen.)
4536
4537    Add a better source for the Zurich 1894 transition.
4538    (Thanks to Pierre-Yves Berger.)
4539
4540    Update shapefile citations in tz-link.htm.  (Thanks to Guy Harris.)
4541
4542
4543Release 2013d - 2013-07-05 07:38:01 -0700
4544
4545  Changes affecting future timestamps:
4546
4547    Morocco's midsummer transitions this year are July 7 and August 10,
4548    not July 9 and August 8.  (Thanks to Andrew Paprocki.)
4549
4550    Israel now falls back on the last Sunday of October.
4551    (Thanks to Ephraim Silverberg.)
4552
4553  Changes affecting past timestamps:
4554
4555    Specify Jerusalem's location more precisely; this changes the pre-1880
4556    times by 2 s.
4557
4558  Changing affecting metadata only:
4559
4560    Fix typos in the entries for country codes BQ and SX.
4561
4562  Changes affecting code:
4563
4564    Rework the code to fix a bug with handling Australia/Macquarie on
4565    32-bit hosts (thanks to Arthur David Olson).
4566
4567    Port to platforms like NetBSD, where time_t can be wider than long.
4568
4569    Add support for testing time_t types other than the system's.
4570    Run 'make check_time_t_alternatives' to try this out.
4571    Currently, the tests fail for unsigned time_t;
4572    this should get fixed at some point.
4573
4574  Changes affecting documentation and commentary:
4575
4576    Deemphasize the significance of national borders.
4577
4578    Update the zdump man page.
4579
4580    Remove obsolete NOID comment (thanks to Denis Excoffier).
4581
4582    Update several URLs and comments in the web pages.
4583
4584    Spelling fixes (thanks to Kevin Lyda and Jonathan Leffler).
4585
4586    Update URL for CLDR Zone->Tzid table (thanks to Yoshito Umaoka).
4587
4588
4589Release 2013c - 2013-04-19 16:17:40 -0700
4590
4591  Changes affecting current and future timestamps:
4592
4593    Palestine observed DST starting March 29, 2013.  (Thanks to
4594    Steffen Thorsen.)  From 2013 on, Gaza and Hebron both observe DST,
4595    with the predicted rules being the last Thursday in March at 24:00
4596    to the first Friday on or after September 21 at 01:00.
4597
4598    Assume that the recent change to Paraguay's DST rules is permanent,
4599    by moving the end of DST to the 4th Sunday in March every year.
4600    (Thanks to Carlos Raúl Perasso.)
4601
4602  Changes affecting past timestamps:
4603
4604    Fix some historical data for Palestine to agree with that of
4605    timeanddate.com, as follows:
4606
4607	  The spring 2008 change in Gaza and Hebron was on 00:00 Mar 28, not
4608	  00:00 Apr 1.
4609
4610	  The fall 2009 change in Gaza and Hebron on Sep 4 was at 01:00, not
4611	  02:00.
4612
4613	  The spring 2010 change in Hebron was 00:00 Mar 26, not 00:01 Mar 27.
4614
4615	  The spring 2011 change in Gaza was 00:01 Apr 1, not 12:01 Apr 2.
4616
4617	  The spring 2011 change in Hebron on Apr 1 was at 00:01, not 12:01.
4618
4619	  The fall 2011 change in Hebron on Sep 30 was at 00:00, not 03:00.
4620
4621    Fix times of habitation for Macquarie to agree with the Tasmania
4622    Parks & Wildlife Service history, which indicates that permanent
4623    habitation was 1899-1919 and 1948 on.
4624
4625  Changing affecting metadata only:
4626
4627    Macquarie Island is politically part of Australia, not Antarctica.
4628    (Thanks to Tobias Conradi.)
4629
4630    Sort Macquarie more consistently with other parts of Australia.
4631    (Thanks to Tim Parenti.)
4632
4633
4634Release 2013b - 2013-03-10 22:33:40 -0700
4635
4636  Changes affecting current and future timestamps:
4637
4638    Haiti uses US daylight-saving rules this year, and presumably future years.
4639    This changes timestamps starting today.  (Thanks to Steffen Thorsen.)
4640
4641    Paraguay will end DST on March 24 this year.
4642    (Thanks to Steffen Thorsen.)  For now, assume it's just this year.
4643
4644    Morocco does not observe DST during Ramadan;
4645    try to predict Ramadan in Morocco as best we can.
4646    (Thanks to Erik Homoet for the heads-up.)
4647
4648  Changes affecting commentary:
4649
4650    Update URLs in tz-link page.  Add URLs for webOS, BB10, iOS.
4651    Update URL for Solaris.  Mention Internet RFC 6557.
4652    Update Internet RFCs 2445->5545, 2822->5322.
4653    Switch from FTP to HTTP for Internet RFCs.
4654
4655
4656Release 2013a - 2013-02-27 09:20:35 -0800
4657
4658  Change affecting binary data format:
4659
4660    The zone offset at the end of version-2-format zone files is now
4661    allowed to be 24:00, as per POSIX.1-2008.  (Thanks to Arthur David Olson.)
4662
4663  Changes affecting current and future timestamps:
4664
4665    Chile's 2013 rules, and we guess rules for 2014 and later, will be
4666    the same as 2012, namely Apr Sun>=23 03:00 UTC to Sep Sun>=2 04:00 UTC.
4667    (Thanks to Steffen Thorsen and Robert Elz.)
4668
4669    New Zones Asia/Khandyga, Asia/Ust-Nera, Europe/Busingen.
4670    (Thanks to Tobias Conradi and Arthur David Olson.)
4671
4672  Many changes affect historical timestamps before 1940.
4673  These were deduced from: Milne J. Civil time. Geogr J. 1899
4674  Feb;13(2):173-94 <https://www.jstor.org/stable/1774359>.
4675
4676  Changes affecting the code:
4677
4678    Fix zic bug that mishandled Egypt's 2010 changes (this also affected
4679    the data).  (Thanks to Arthur David Olson.)
4680
4681    Fix localtime bug when time_t is unsigned and data files were generated
4682    by a signed time_t system.  (Thanks to Doug Bailey for reporting and
4683    to Arthur David Olson for fixing.)
4684
4685    Allow the email address for bug reports to be set by the packager.
4686    The default is tz@iana.org, as before.  (Thanks to Joseph S. Myers.)
4687
4688    Update HTML checking to be compatible with Ubuntu 12.10.
4689
4690    Check that files are a safe subset of ASCII.  At some point we may
4691    relax this requirement to a safe subset of UTF-8.  Without the
4692    check, some non-UTF-8 encodings were leaking into the distribution.
4693
4694  Commentary changes:
4695
4696    Restore a comment about copyright notices that was inadvertently deleted.
4697    (Thanks to Arthur David Olson.)
4698
4699    Improve the commentary about which districts observe what times
4700    in Russia.  (Thanks to Oscar van Vlijmen and Arthur David Olson.)
4701
4702    Add web page links to tz.js.
4703
4704    Add "Run by the Monkeys" to tz-art.  (Thanks to Arthur David Olson.)
4705
4706
4707Release 2012j - 2012-11-12 18:34:49 -0800
4708
4709  Libya moved to CET this weekend, but with DST planned next year.
4710  (Thanks to Even Scharning, Steffen Thorsen, and Tim Parenti.)
4711
4712  Signatures now have the extension .asc, not .sign, as that's more
4713  standard.  (Thanks to Phil Pennock.)
4714
4715  The output of 'zdump --version', and of 'zic --version', now
4716  uses a format that is more typical for --version.
4717  (Thanks to Joseph S. Myers.)
4718
4719  The output of 'tzselect --help', 'zdump --help', and 'zic --help'
4720  now uses tz@iana.org rather than the old elsie address.
4721
4722  zic -v now complains about abbreviations that are less than 3
4723  or more than 6 characters, as per POSIX.  Formerly, it checked
4724  for abbreviations that were more than 3.
4725
4726  'make public' no longer puts its temporary directory under /tmp,
4727  and uses the just-built zic rather than the system zic.
4728
4729  Various fixes to documentation and commentary.
4730
4731
4732Release 2012i - 2012-11-03 12:57:09 -0700
4733
4734  Cuba switches from DST tomorrow at 01:00.  (Thanks to Steffen Thorsen.)
4735
4736  Linker flags can now be specified via LDFLAGS.
4737  AWK now defaults to 'awk', not 'nawk'.
4738  The shell in tzselect now defaults to /bin/bash, but this can
4739  be overridden by specifying KSHELL.
4740  The main web page now mentions the unofficial GitHub repository.
4741  (Thanks to Mike Frysinger.)
4742
4743  Tarball signatures can now be built by running 'make signatures'.
4744  There are also new makefile rules 'tarballs', 'check_public', and
4745  separate makefile rules for each tarball and signature file.
4746  A few makefile rules are now more portable to strict POSIX.
4747
4748  The main web page now lists the canonical IANA URL.
4749
4750
4751Release 2012h - 2012-10-26 22:49:10 -0700
4752
4753  Bahia no longer has DST.  (Thanks to Kelley Cook.)
4754
4755  Tocantins has DST.  (Thanks to Rodrigo Severo.)
4756
4757  Israel has new DST rules next year.  (Thanks to Ephraim Silverberg.)
4758
4759  Jordan stays on DST this winter.  (Thanks to Steffen Thorsen.)
4760
4761  Web page updates.
4762
4763  More C modernization, except that at Arthur David Olson's suggestion
4764  the instances of 'register' were kept.
4765
4766
4767Release 2012g - 2012-10-17 20:59:45 -0700
4768
4769  Samoa fall 2012 and later.  (Thanks to Nicholas Pereira and Robert Elz.)
4770
4771  Palestine fall 2012.  (Thanks to Steffen Thorsen.)
4772
4773  Assume C89.
4774
4775  To attack the version-number problem, this release ships the file
4776  'Makefile' (which contains the release number) in both the tzcode and
4777  the tzdata tarballs.  The two Makefiles are identical, and should be
4778  identical in any matching pair of tarballs, so it shouldn't matter
4779  which order you extract the tarballs.  Perhaps we can come up with a
4780  better version-number scheme at some point; this scheme does have the
4781  virtue of not adding more files.
4782
4783
4784Release 2012f - 2012-09-12 23:17:03 -0700
4785
4786  * australasia (Pacific/Fiji): Fiji DST is October 21 through January
4787    20 this year.  (Thanks to Steffen Thorsen.)
4788
4789
4790Release 2012e - 2012-08-02 20:44:55 -0700
4791
4792  * australasia (Pacific/Fakaofo): Tokelau is UT +13, not +14.
4793    (Thanks to Steffen Thorsen.)
4794
4795  * Use a single version number for both code and data.
4796
4797  * .gitignore: New file.
4798
4799  * Remove trailing white space.
4800
4801
4802Release code2012c-data2012d - 2012-07-19 16:35:33 -0700
4803
4804  Changes for Morocco's timestamps, which take effect in a couple of
4805  hours, along with infrastructure changes to accommodate how the tz
4806  code and data are released on IANA.
4807
4808
4809Release data2012c - 2012-03-27 12:17:25 -0400
4810
4811  africa
4812	Summer time changes for Morocco (to start late April 2012)
4813
4814  asia
4815	Changes for 2012 for Gaza & the West Bank (Hebron) and Syria
4816
4817  northamerica
4818	Haiti following US/Canada rules for 2012 (and we're assuming,
4819	for now anyway, for the future).
4820
4821
4822Release 2012b - 2012-03-02 12:29:15 +0700
4823
4824  There is just one change to tzcode2012b (compared with 2012a):
4825  the Makefile that was accidentally included with 2012a has been
4826  replaced with the version that should have been there, which is
4827  identical with the previous version (from tzcode2011i).
4828
4829  There are just two changes in tzdata2012b compared with 2012a.
4830
4831  Most significantly, summer time in Cuba has been delayed 3 weeks
4832  (now starts April 1 rather than March 11).   Since Mar 11 (the old start
4833  date, as listed in 2012a) is just a little over a week away, this
4834  change is urgent.
4835
4836  Less importantly, an excess tab in one of the changes in zone.tab
4837  in 2012a has been removed.
4838
4839
4840Release 2012a - 2012-03-01 18:28:10 +0700
4841
4842  The changes in tzcode2012a (compared to the previous version, 2011i)
4843  are entirely to the README and tz-art.htm and tz-link.htm files, if
4844  none of those concern you, you can ignore the code update.  The changes
4845  reflect the changed addresses for the mailing list and the code and
4846  data distribution points & methods (and a link to DateTime::TimeZone::Tzfile
4847  has been added to tz-link.htm).
4848
4849  In tzdata2012a (compared to the previous release, which was 2011n)
4850  the major changes are:
4851	Chile 2011/2012 and 2012/2013 summer time date adjustments.
4852	Falkland Islands onto permanent summer time (we're assuming for the
4853		foreseeable future, though 2012 is all we're fairly certain of.)
4854	Armenia has abolished Summer Time.
4855	Tokelau jumped the International Date Line back last December
4856		(just the same as their near neighbour, Samoa).
4857	America/Creston is a new zone for a small area of British Columbia
4858	There will be a leapsecond 2012-06-30 23:59:60 UTC.
4859
4860  Other minor changes are:
4861	Corrections to 1918 Canadian summer time end dates.
4862	Updated URL for UK time zone history (in comments)
4863	A few typos in Le Corre's list of free French place names (comments)
4864
4865
4866Release data2011n - 2011-10-30 14:57:54 +0700
4867
4868  There are three changes of note - most urgently, Cuba (America/Havana)
4869  has extended summer time by two weeks, now to end on Nov 13, rather than
4870  the (already past) Oct 30.   Second, the Pridnestrovian Moldavian Republic
4871  (Europe/Tiraspol) decided not to split from the rest of Moldova after
4872  all, and consequently that zone has been removed (again) and reinstated
4873  in the "backward" file as a link to Europe/Chisinau.   And third, the
4874  end date for Fiji's summer time this summer was moved forward from the
4875  earlier planned Feb 26, to Jan 22.
4876
4877  Apart from that, Moldova (MD) returns to a single entry in zone.tab
4878  (and the incorrect syntax that was in the 2011m version of that file
4879  is so fixed - it would have been fixed in a different way had this
4880  change not happened - that's the "missing" sccs version id).
4881
4882
4883Release data2011m - 2011-10-24 21:42:16 +0700
4884
4885  In particular, the typos in comments in the data (2011-11-17 should have
4886  been 2011-10-17 as Alan Barrett noted, and spelling of Tiraspol that
4887  Tim Parenti noted) have been fixed, and the change for Ukraine has been
4888  made in all 4 Ukrainian zones, rather than just Europe/Kiev
4889  (again, thanks to Tim Parenti, and also Denys Gavrysh).
4890
4891  In addition, I added Europe/Tiraspol to zone.tab.
4892
4893  This time, all the files have new version numbers...  (including the files
4894  otherwise unchanged in 2011m that were changed in 2011l but didn't get new
4895  version numbers there...)
4896
4897
4898Release data2011l - 2011-10-10 11:15:43 +0700
4899
4900  There are just 2 changes that cause different generated tzdata files from
4901  zic, to Asia/Hebron and Pacific/Fiji - the possible change for Bahia, Brazil
4902  is included, but commented out.  Compared with the diff I sent out last week,
4903  this version also includes attributions for the sources for the changes
4904  (in much the same format as ado used, but the html tags have not been
4905  checked, verified, or used in any way at all, so if there are errors there,
4906  please let me know.)
4907
4908
4909Release data2011k - 2011-09-20 17:54:03 -0400
4910
4911  [not summarized]
4912
4913
4914Release data2011j - 2011-09-12 09:22:49 -0400
4915
4916  (contemporary changes for Samoa; past changes for Kenya, Uganda, and
4917  Tanzania); there are also two spelling corrections to comments in
4918  the australasia file (with thanks to Christos Zoulas).
4919
4920
4921Release 2011i - 2011-08-29 05:56:32 -0400
4922
4923  [not summarized]
4924
4925
4926Release data2011h - 2011-06-15 18:41:48 -0400
4927
4928  Russia and Curaçao changes
4929
4930
4931Release 2011g - 2011-04-25 09:07:22 -0400
4932
4933  update the rules for Egypt to reflect its abandonment of DST this year
4934
4935
4936Release 2011f - 2011-04-06 17:14:53 -0400
4937
4938  [not summarized]
4939
4940
4941Release 2011e - 2011-03-31 16:04:38 -0400
4942
4943  Morocco, Chile, and tz-link changes
4944
4945
4946Release 2011d - 2011-03-14 09:18:01 -0400
4947
4948  changes that impact present-day timestamps in Cuba, Samoa, and Turkey
4949
4950
4951Release 2011c - 2011-03-07 09:30:09 -0500
4952
4953  These do affect current timestamps in Chile and Annette Island, Canada.
4954
4955
4956Release 2011b - 2011-02-07 08:44:50 -0500
4957
4958  [not summarized]
4959
4960
4961Release 2011a - 2011-01-24 10:30:16 -0500
4962
4963  [not summarized]
4964
4965
4966Release data2010o - 2010-11-01 09:18:23 -0400
4967
4968  change to the end of DST in Fiji in 2011
4969
4970
4971Release 2010n - 2010-10-25 08:19:17 -0400
4972
4973  [not summarized]
4974
4975
4976Release 2010m - 2010-09-27 09:24:48 -0400
4977
4978  Hong Kong, Vostok, and zic.c changes
4979
4980
4981Release 2010l - 2010-08-16 06:57:25 -0400
4982
4983  [not summarized]
4984
4985
4986Release 2010k - 2010-07-26 10:42:27 -0400
4987
4988  [not summarized]
4989
4990
4991Release 2010j - 2010-05-10 09:07:48 -0400
4992
4993  changes for Bahía de Banderas and for version naming
4994
4995
4996Release data2010i - 2010-04-16 18:50:45 -0400
4997
4998  the end of DST in Morocco on 2010-08-08
4999
5000
5001Release data2010h - 2010-04-05 09:58:56 -0400
5002
5003  [not summarized]
5004
5005
5006Release data2010g - 2010-03-24 11:14:53 -0400
5007
5008  [not summarized]
5009
5010
5011Release 2010f - 2010-03-22 09:45:46 -0400
5012
5013  [not summarized]
5014
5015
5016Release data2010e - 2010-03-08 14:24:27 -0500
5017
5018  corrects the Dhaka bug found by Danvin Ruangchan
5019
5020
5021Release data2010d - 2010-03-06 07:26:01 -0500
5022
5023  [not summarized]
5024
5025
5026Release 2010c - 2010-03-01 09:20:58 -0500
5027
5028  changes including KRE's suggestion for earlier initialization of
5029  "goahead" and "goback" structure elements
5030
5031
5032Release code2010a - 2010-02-16 10:40:04 -0500
5033
5034  [not summarized]
5035
5036
5037Release data2010b - 2010-01-20 12:37:01 -0500
5038
5039  Mexico changes
5040
5041
5042Release data2010a - 2010-01-18 08:30:04 -0500
5043
5044  changes to Dhaka
5045
5046
5047Release data2009u - 2009-12-26 08:32:28 -0500
5048
5049  changes to DST in Bangladesh
5050
5051
5052Release 2009t - 2009-12-21 13:24:27 -0500
5053
5054  [not summarized]
5055
5056
5057Release data2009s - 2009-11-14 10:26:32 -0500
5058
5059  (cosmetic) Antarctica change and the DST-in-Fiji-in-2009-and-2010 change
5060
5061
5062Release 2009r - 2009-11-09 10:10:31 -0500
5063
5064  "antarctica" and "tz-link.htm" changes
5065
5066
5067Release 2009q - 2009-11-02 09:12:40 -0500
5068
5069  with two corrections as reported by Eric Muller and Philip Newton
5070
5071
5072Release data2009p - 2009-10-23 15:05:27 -0400
5073
5074  Argentina (including San Luis) changes (with the correction from
5075  Mariano Absatz)
5076
5077
5078Release data2009o - 2009-10-14 16:49:38 -0400
5079
5080  Samoa (commentary only), Pakistan, and Bangladesh changes
5081
5082
5083Release data2009n - 2009-09-22 15:13:38 -0400
5084
5085  added commentary for Argentina and a change to the end of DST in
5086  2009 in Pakistan
5087
5088
5089Release data2009m - 2009-09-03 10:23:43 -0400
5090
5091  Samoa and Palestine changes
5092
5093
5094Release data2009l - 2009-08-14 09:13:07 -0400
5095
5096  Samoa (comments only) and Egypt
5097
5098
5099Release 2009k - 2009-07-20 09:46:08 -0400
5100
5101  [not summarized]
5102
5103
5104Release data2009j - 2009-06-15 06:43:59 -0400
5105
5106  Bangladesh change (with a short turnaround since the DST change is
5107  impending)
5108
5109
5110Release 2009i - 2009-06-08 09:21:22 -0400
5111
5112  updating for DST in Bangladesh this year
5113
5114
5115Release 2009h - 2009-05-26 09:19:14 -0400
5116
5117  [not summarized]
5118
5119
5120Release data2009g - 2009-04-20 16:34:07 -0400
5121
5122  Cairo
5123
5124
5125Release data2009f - 2009-04-10 11:00:52 -0400
5126
5127  correct DST in Pakistan
5128
5129
5130Release 2009e - 2009-04-06 09:08:11 -0400
5131
5132  [not summarized]
5133
5134
5135Release 2009d - 2009-03-23 09:38:12 -0400
5136
5137  Morocco, Tunisia, Argentina, and American Astronomical Society changes
5138
5139
5140Release data2009c - 2009-03-16 09:47:51 -0400
5141
5142  change to the start of Cuban DST
5143
5144
5145Release 2009b - 2009-02-09 11:15:22 -0500
5146
5147  [not summarized]
5148
5149
5150Release 2009a - 2009-01-21 10:09:39 -0500
5151
5152  [not summarized]
5153
5154
5155Release data2008i - 2008-10-21 12:10:25 -0400
5156
5157  southamerica and zone.tab files, with Argentina DST rule changes and
5158  United States zone reordering and recommenting
5159
5160
5161Release 2008h - 2008-10-13 07:33:56 -0400
5162
5163  [not summarized]
5164
5165
5166Release 2008g - 2008-10-06 09:03:18 -0400
5167
5168  Fix a broken HTML anchor and update Brazil's DST transitions;
5169  there's also a slight reordering of information in tz-art.htm.
5170
5171
5172Release data2008f - 2008-09-09 22:33:26 -0400
5173
5174  [not summarized]
5175
5176
5177Release 2008e - 2008-07-28 14:11:17 -0400
5178
5179  changes by Arthur David Olson and Jesper Nørgaard Welen
5180
5181
5182Release data2008d - 2008-07-07 09:51:38 -0400
5183
5184  changes by Arthur David Olson, Paul Eggert, and Rodrigo Severo
5185
5186
5187Release data2008c - 2008-05-19 17:48:03 -0400
5188
5189  Pakistan, Morocco, and Mongolia
5190
5191
5192Release data2008b - 2008-03-24 08:30:59 -0400
5193
5194  including renaming Asia/Calcutta to Asia/Kolkata, with a backward
5195  link provided
5196
5197
5198Release 2008a - 2008-03-08 05:42:16 -0500
5199
5200  [not summarized]
5201
5202
5203Release 2007k - 2007-12-31 10:25:22 -0500
5204
5205  most importantly, changes to the "southamerica" file based on
5206  Argentina's readoption of daylight saving time
5207
5208
5209Release 2007j - 2007-12-03 09:51:01 -0500
5210
5211  1. eliminate the "P" (parameter) macro;
5212
5213  2. the "noncontroversial" changes circulated on the time zone
5214  mailing list (less the changes to "logwtmp.c");
5215
5216  3. eliminate "too many transition" errors when "min" is used in time
5217  zone rules;
5218
5219  4. changes by Paul Eggert (including updated information for Venezuela).
5220
5221
5222Release data2007i - 2007-10-30 10:28:11 -0400
5223
5224  changes for Cuba and Syria
5225
5226
5227Release 2007h - 2007-10-01 10:05:51 -0400
5228
5229  changes by Paul Eggert, as well as an updated link to the ICU
5230  project in tz-link.htm
5231
5232
5233Release 2007g - 2007-08-20 10:47:59 -0400
5234
5235  changes by Paul Eggert
5236
5237  The "leapseconds" file has been updated to incorporate the most
5238  recent International Earth Rotation and Reference Systems Service
5239  (IERS) bulletin.
5240
5241  There's an addition to tz-art.htm regarding the television show "Medium".
5242
5243
5244Release 2007f - 2007-05-07 10:46:46 -0400
5245
5246  changes by Paul Eggert (including Haiti, Turks and Caicos, and New
5247  Zealand)
5248
5249  changes to zic.c to allow hour values greater than 24 (along with
5250  Paul's improved time value overflow checking)
5251
5252
5253Release 2007e - 2007-04-02 10:11:52 -0400
5254
5255  Syria and Honduras changes by Paul Eggert
5256
5257  zic.c variable renaming changes by Arthur David Olson
5258
5259
5260Release 2007d - 2007-03-20 08:48:30 -0400
5261
5262  changes by Paul Eggert
5263
5264  the elimination of white space at the ends of lines
5265
5266
5267Release 2007c - 2007-02-26 09:09:37 -0500
5268
5269  changes by Paul Eggert
5270
5271
5272Release 2007b - 2007-02-12 09:34:20 -0500
5273
5274  Paul Eggert's proposed change to the quotation handling logic in zic.c.
5275
5276  changes to the commentary in "leapseconds" reflecting the IERS
5277  announcement that there is to be no positive leap second at the end
5278  of June 2007.
5279
5280
5281Release 2007a - 2007-01-08 12:28:29 -0500
5282
5283  changes by Paul Eggert
5284
5285  Derick Rethans's Asmara change
5286
5287  Oscar van Vlijmen's Easter Island local mean time change
5288
5289  symbolic link changes
5290
5291
5292Release 2006p - 2006-11-27 08:54:27 -0500
5293
5294  changes by Paul Eggert
5295
5296
5297Release 2006o - 2006-11-06 09:18:07 -0500
5298
5299  changes by Paul Eggert
5300
5301
5302Release 2006n - 2006-10-10 11:32:06 -0400
5303
5304  changes by Paul Eggert
5305
5306
5307Release 2006m - 2006-10-02 15:32:35 -0400
5308
5309  changes for Uruguay, Palestine, and Egypt by Paul Eggert
5310
5311  (minimalist) changes to zic.8 to clarify "until" information
5312
5313
5314Release data2006l - 2006-09-18 12:58:11 -0400
5315
5316  Paul's best-effort work on this coming weekend's Egypt time change
5317
5318
5319Release 2006k - 2006-08-28 12:19:09 -0400
5320
5321  changes by Paul Eggert
5322
5323
5324Release 2006j - 2006-08-21 09:56:32 -0400
5325
5326  changes by Paul Eggert
5327
5328
5329Release code2006i - 2006-08-07 12:30:55 -0400
5330
5331  localtime.c fixes
5332
5333  Ken Pizzini's conversion script
5334
5335
5336Release code2006h - 2006-07-24 09:19:37 -0400
5337
5338  adds public domain notices to four files
5339
5340  includes a fix for transition times being off by a second
5341
5342  adds a new recording to the "arts" file (information courtesy Colin Bowern)
5343
5344
5345Release 2006g - 2006-05-08 17:18:09 -0400
5346
5347  northamerica changes by Paul Eggert
5348
5349
5350Release 2006f - 2006-05-01 11:46:00 -0400
5351
5352  a missing version number problem is fixed (with thanks to Bradley
5353  White for catching the problem)
5354
5355
5356Release 2006d - 2006-04-17 14:33:43 -0400
5357
5358  changes by Paul Eggert
5359
5360  added new items to tz-arts.htm that were found by Paul
5361
5362
5363Release 2006c - 2006-04-03 10:09:32 -0400
5364
5365  two sets of data changes by Paul Eggert
5366
5367  a fencepost error fix in zic.c
5368
5369  changes to zic.c and the "europe" file to minimize differences
5370  between output produced by the old 32-bit zic and the new 64-bit
5371  version
5372
5373
5374Release 2006b - 2006-02-20 10:08:18 -0500
5375  [tz32code2006b + tz64code2006b + tzdata2006b]
5376
5377  64-bit code
5378
5379  All SCCS IDs were bumped to "8.1" for this release.
5380
5381
5382Release 2006a - 2006-01-30 08:59:31 -0500
5383
5384  changes by Paul Eggert (in particular, Indiana time zone moves)
5385
5386  an addition to the zic manual page to describe how special-case
5387  transitions are handled
5388
5389
5390Release 2005r - 2005-12-27 09:27:13 -0500
5391
5392  Canadian changes by Paul Eggert
5393
5394  They also add "<pre>" directives to time zone data files and reflect
5395  changes to warning message logic in "zdump.c" (but with calls to
5396  "gettext" kept unbundled at the suggestion of Ken Pizzini).
5397
5398
5399Release 2005q - 2005-12-13 09:17:09 -0500
5400
5401  Nothing earth-shaking here:
5402	1.  Electronic mail addresses have been removed.
5403	2.  Casts of the return value of exit have been removed.
5404	3.  Casts of the argument of is.* macros have been added.
5405	4.  Indentation in one section of zic.c has been fixed.
5406	5.  References to dead URLs in the data files have been dealt with.
5407
5408
5409Release 2005p - 2005-12-05 10:30:53 -0500
5410
5411  "systemv", "tz-link.htm", and "zdump.c" changes
5412  (less the casts of arguments to the is* macros)
5413
5414
5415Release 2005o - 2005-11-28 10:55:26 -0500
5416
5417  Georgia, Cuba, Nicaragua, and Jordan changes by Paul Eggert
5418
5419  zdump.c lint fixes by Arthur David Olson
5420
5421
5422Release 2005n - 2005-10-03 09:44:09 -0400
5423
5424  changes by Paul Eggert (both the Uruguay changes and the Kyrgyzstan
5425  et al. changes)
5426
5427
5428Release 2005m - 2005-08-29 12:15:40 -0400
5429
5430  changes by Paul Eggert (with a small tweak to the tz-art change)
5431
5432  a declaration of an unused variable has been removed from zdump.c
5433
5434
5435Release 2005l - 2005-08-22 12:06:39 -0400
5436
5437  changes by Paul Eggert
5438
5439  overflow/underflow checks by Arthur David Olson, minus changes to
5440  the "Theory" file about the pending addition of 64-bit data (I grow
5441  less confident of the changes being accepted with each passing day,
5442  and the changes no longer increase the data files nine-fold--there's
5443  less than a doubling in size by my local Sun's reckoning)
5444
5445
5446Release 2005k - 2005-07-14 14:14:24 -0400
5447
5448  The "leapseconds" file has been edited to reflect the recently
5449  announced leap second at the end of 2005.
5450
5451  I've also deleted electronic mail addresses from the files as an
5452  anti-spam measure.
5453
5454
5455Release 2005j - 2005-06-13 14:34:13 -0400
5456
5457  These reflect changes to limit the length of time zone abbreviations
5458  and the characters used in those abbreviations.
5459
5460  There are also changes to handle POSIX-style "quoted" timezone
5461  environment variables.
5462
5463  The changes were circulated on the time zone mailing list; the only
5464  change since then was the removal of a couple of minimum-length of
5465  abbreviation checks.
5466
5467
5468Release data2005i - 2005-04-21 15:04:16 -0400
5469
5470  changes (most importantly to Nicaragua and Haiti) by Paul Eggert
5471
5472
5473Release 2005h - 2005-04-04 11:24:47 -0400
5474
5475  changes by Paul Eggert
5476
5477  minor changes to Makefile and zdump.c to produce more useful output
5478  when doing a "make typecheck"
5479
5480
5481Release 2005g - 2005-03-14 10:11:21 -0500
5482
5483  changes by Paul Eggert (a change to current DST rules in Uruguay and
5484  an update to a link to time zone software)
5485
5486
5487Release 2005f - 2005-03-01 08:45:32 -0500
5488
5489  data and documentation changes by Paul Eggert
5490
5491
5492Release 2005e - 2005-02-10 15:59:44 -0500
5493
5494  [not summarized]
5495
5496
5497Release code2005d - 2005-01-31 09:21:47 -0500
5498
5499  make zic complain about links to links if the -v flag is used
5500
5501  have "make public" do more code checking
5502
5503  add an include to "localtime.c" for the benefit of gcc systems
5504
5505
5506Release 2005c - 2005-01-17 18:36:29 -0500
5507
5508  get better results when mktime runs on a system where time_t is double
5509
5510  changes to the data files (most importantly to Paraguay)
5511
5512
5513Release 2005b - 2005-01-10 09:19:54 -0500
5514
5515  Get localtime and gmtime working on systems with exotic time_t types.
5516
5517  Update the leap second commentary in the "leapseconds" file.
5518
5519
5520Release 2005a - 2005-01-01 13:13:44 -0500
5521
5522  [not summarized]
5523
5524
5525Release code2004i - 2004-12-14 13:42:58 -0500
5526
5527  Deal with systems where time_t is unsigned.
5528
5529
5530Release code2004h - 2004-12-07 11:40:18 -0500
5531
5532  64-bit-time_t changes
5533
5534
5535Release 2004g - 2004-11-02 09:06:01 -0500
5536
5537  update to Cuba (taking effect this weekend)
5538
5539  other changes by Paul Eggert
5540
5541  correction of the spelling of Oslo
5542
5543  changed versions of difftime.c and private.h
5544
5545
5546Release code2004f - 2004-10-21 10:25:22 -0400
5547
5548  Cope with wide-ranging tm_year values.
5549
5550
5551Release 2004e - 2004-10-11 14:47:21 -0400
5552
5553  Brazil/Argentina/Israel changes by Paul Eggert
5554
5555  changes to tz-link.htm by Paul
5556
5557  one small fix to Makefile
5558
5559
5560Release 2004d - 2004-09-22 08:27:29 -0400
5561
5562  Avoid overflow problems when TM_YEAR_BASE is added to an integer.
5563
5564
5565Release 2004c - 2004-08-11 12:06:26 -0400
5566
5567  asctime-related changes
5568
5569  (variants of) some of the documentation changes suggested by Paul Eggert
5570
5571
5572Release 2004b - 2004-07-19 14:33:35 -0400
5573
5574  data changes by Paul Eggert - most importantly, updates for Argentina
5575
5576
5577Release 2004a - 2004-05-27 12:00:47 -0400
5578
5579  changes by Paul Eggert
5580
5581  Handle DST transitions that occur at the end of a month in some
5582  years but at the start of the following month in other years.
5583
5584  Add a copy of the correspondence that's the basis for claims about
5585  DST in the Navajo Nation.
5586
5587
5588Release 2003e - 2003-12-15 09:36:47 -0500
5589
5590  changes by Arthur David Olson (primarily code changes)
5591
5592  changes by Paul Eggert (primarily data changes)
5593
5594  minor changes to "Makefile" and "northamerica" (in the latter case,
5595  optimization of the "Toronto" rules)
5596
5597
5598Release 2003d - 2003-10-06 09:34:44 -0400
5599
5600  changes by Paul Eggert
5601
5602
5603Release 2003c - 2003-09-16 10:47:05 -0400
5604
5605  Fix bad returns in zic.c's inleap function.
5606  Thanks to Bradley White for catching the problem!
5607
5608
5609Release 2003b - 2003-09-16 07:13:44 -0400
5610
5611  Add a "--version" option (and documentation) to the zic and zdump commands.
5612
5613  changes to overflow/underflow checking in zic
5614
5615  a localtime typo fix.
5616
5617  Update the leapseconds and tz-art.htm files.
5618
5619
5620Release 2003a - 2003-03-24 09:30:54 -0500
5621
5622  changes by Paul Eggert
5623
5624  a few additions and modifications to the tz-art.htm file
5625
5626
5627Release 2002d - 2002-10-15 13:12:42 -0400
5628
5629  changes by Paul Eggert, less the "Britain (UK)" change in iso3166.tab
5630
5631  There's also a new time zone quote in "tz-art.htm".
5632
5633
5634Release 2002c - 2002-04-04 11:55:20 -0500
5635
5636  changes by Paul Eggert
5637
5638  Change zic.c to avoid creating symlinks to files that don't exist.
5639
5640
5641Release 2002b - 2002-01-28 12:56:03 -0500
5642
5643  [These change notes are for Release 2002a, which was corrupted.
5644  2002b was a corrected version of 2002a.]
5645
5646  changes by Paul Eggert
5647
5648  Update the "leapseconds" file to note that there'll be no leap
5649  second at the end of June, 2002.
5650
5651  Change "zic.c" to deal with a problem in handling the "Asia/Bishkek" zone.
5652
5653  Change to "difftime.c" to avoid sizeof problems.
5654
5655
5656Release 2001d - 2001-10-09 13:31:32 -0400
5657
5658  changes by Paul Eggert
5659
5660
5661Release 2001c - 2001-06-05 13:59:55 -0400
5662
5663  changes by Paul Eggert and Andrew Brown
5664
5665
5666Release 2001b - 2001-04-05 16:44:38 -0400
5667
5668  changes by Paul Eggert (modulo jnorgard's typo fix)
5669
5670  tz-art.htm has been HTMLified.
5671
5672
5673Release 2001a - 2001-03-13 12:57:44 -0500
5674
5675  changes by Paul Eggert
5676
5677  An addition to the "leapseconds" file: comments with the text of the
5678  latest IERS leap second notice.
5679
5680  Trailing white space has been removed from data file lines, and
5681  repeated spaces in "Rule Jordan" lines in the "asia" file have been
5682  converted to tabs.
5683
5684
5685Release 2000h - 2000-12-14 15:33:38 -0500
5686
5687  changes by Paul Eggert
5688
5689  one typo fix in the "art" file
5690
5691  With providence, this is the last update of the millennium.
5692
5693
5694Release 2000g - 2000-10-10 11:35:22 -0400
5695
5696  changes by Paul Eggert
5697
5698  correction of John Mackin's name submitted by Robert Elz
5699
5700  Garry Shandling's Daylight Saving Time joke (!?!) from the recent
5701  Emmy Awards broadcast.
5702
5703
5704Release 2000f - 2000-08-10 09:31:58 -0400
5705
5706  changes by Paul Eggert
5707
5708  Added information in "tz-art.htm" on a Seinfeld reference to DST.
5709
5710  Error checking and messages in the "yearistype" script have been
5711  improved.
5712
5713
5714Release 2000e - 2000-07-31 09:27:54 -0400
5715
5716  data changes by Paul Eggert
5717
5718  a change to the default value of the defined constant HAVE_STRERROR
5719
5720  the addition of a Dave Barry quote on DST to the tz-arts file
5721
5722
5723Release 2000d - 2000-04-20 15:43:04 -0400
5724
5725  changes to the documentation and code of strftime for C99 conformance
5726
5727  a bug fix for date.c
5728
5729  These are based on (though modified from) changes by Paul Eggert.
5730
5731
5732Release 2000c - 2000-03-04 10:31:43 -0500
5733
5734  changes by Paul Eggert
5735
5736
5737Release 2000b - 2000-02-21 12:16:29 -0500
5738
5739  changes by Paul Eggert and Joseph Myers
5740
5741  modest tweaks to the tz-art.htm and tz-link.htm files
5742
5743
5744Release 2000a - 2000-01-18 09:21:26 -0500
5745
5746  changes by Paul Eggert
5747
5748  The two hypertext documents have also been renamed.
5749
5750
5751Release code1999i-data1999j - 1999-11-15 18:43:22 -0500
5752
5753  Paul Eggert's changes
5754
5755  additions to the "zic" manual page and the "Arts.htm" file
5756
5757
5758Release code1999h-data1999i - 1999-11-08 14:55:21 -0500
5759
5760  [not summarized]
5761
5762
5763Release data1999h - 1999-10-07 03:50:29 -0400
5764
5765  changes by Paul Eggert to "europe" (most importantly, fixing
5766  Lithuania and Estonia)
5767
5768
5769Release 1999g - 1999-09-28 11:06:18 -0400
5770
5771  data changes by Paul Eggert (most importantly, the change for
5772  Lebanon that buys correctness for this coming Sunday)
5773
5774  The "code" file contains changes to "Makefile" and "checktab.awk" to
5775  allow better checking of time zone files before they are published.
5776
5777
5778Release 1999f - 1999-09-23 09:48:14 -0400
5779
5780  changes by Arthur David Olson and Paul Eggert
5781
5782
5783Release 1999e - 1999-08-17 15:20:54 -0400
5784
5785  changes circulated by Paul Eggert, although the change to handling
5786  of DST-specifying timezone names has been commented out for now
5787  (search for "XXX" in "localtime.c" for details).  These files also
5788  do not make any changes to the start of DST in Brazil.
5789
5790  In addition to Paul's changes, there are updates to "Arts.htm" and
5791  cleanups of URLs.
5792
5793
5794Release 1999d - 1999-03-30 11:31:07 -0500
5795
5796  changes by Paul Eggert
5797
5798  The Makefile's "make public" rule has also been changed to do a test
5799  compile of each individual time zone data file (which should help
5800  avoid problems such as the one we had with Nicosia).
5801
5802
5803Release 1999c - 1999-03-25 09:47:47 -0500
5804
5805  changes by Paul Eggert, most importantly the change for Chile.
5806
5807
5808Release 1999b - 1999-02-01 17:51:44 -0500
5809
5810  changes by Paul Eggert
5811
5812  code changes (suggested by Mani Varadarajan, mani at be.com) for
5813  correct handling of symbolic links when building using a relative directory
5814
5815  code changes to generate correct messages for failed links
5816
5817  updates to the URLs in Arts.htm
5818
5819
5820Release 1999a - 1999-01-19 16:20:29 -0500
5821
5822  error message internationalizations and corrections in zic.c and
5823  zdump.c (as suggested by Vladimir Michl, vladimir.michl at upol.cz,
5824  to whom thanks!)
5825
5826
5827Release code1998h-data1998i - 1998-10-01 09:56:10 -0400
5828
5829  changes for Brazil, Chile, and Germany
5830
5831  support for use of "24:00" in the input files for the time zone compiler
5832
5833
5834Release code1998g-data1998h - 1998-09-24 10:50:28 -0400
5835
5836  changes by Paul Eggert
5837
5838  correction to a define in the "private.h" file
5839
5840
5841Release data1998g - 1998-08-11 03:28:35 -0000
5842  [tzdata1998g.tar.gz is missing!]
5843
5844  Lithuanian change provided by mgedmin at pub.osf.it
5845
5846  Move creation of the GMT link with Etc/GMT to "etcetera" (from
5847  "backward") to ensure that the GMT file is created even where folks
5848  don't want the "backward" links (as suggested by Paul Eggert).
5849
5850
5851Release data1998f - 1998-07-20 13:50:00 -0000
5852  [tzdata1998f.tar.gz is missing!]
5853
5854  Update the "leapseconds" file to include the newly announced
5855  insertion at the end of 1998.
5856
5857
5858Release code1998f - 1998-06-01 10:18:31 -0400
5859
5860  addition to localtime.c by Guy Harris
5861
5862
5863Release 1998e - 1998-05-28 09:56:26 -0400
5864
5865  The Makefile is changed to produce zoneinfo-posix rather than
5866  zoneinfo/posix, and to produce zoneinfo-leaps rather than
5867  zoneinfo/right.
5868
5869  data changes by Paul Eggert
5870
5871  changes from Guy Harris to provide asctime_r and ctime_r
5872
5873  A usno1998 file (substantially identical to usno1997) has been added.
5874
5875
5876Release 1998d - 1998-05-14 11:58:34 -0400
5877
5878  changes to comments (in particular, elimination of references to CIA maps).
5879  "Arts.htm", "WWW.htm", "asia", and "australasia" are the only places
5880  where changes occur.
5881
5882
5883Release 1998c - 1998-02-28 12:32:26 -0500
5884
5885  changes by Paul Eggert (save the "French correction," on which I'll
5886  wait for the dust to settle)
5887
5888  symlink changes
5889
5890  changes and additions to Arts.htm
5891
5892
5893Release 1998b - 1998-01-17 14:31:51 -0500
5894
5895  URL cleanups and additions
5896
5897
5898Release 1998a - 1998-01-13 12:37:35 -0500
5899
5900  changes by Paul Eggert
5901
5902
5903Release code1997i-data1997k - 1997-12-29 09:53:41 -0500
5904
5905  changes by Paul Eggert, with minor modifications from Arthur David
5906  Olson to make the files more browser friendly
5907
5908
5909Release code1997h-data1997j - 1997-12-18 17:47:35 -0500
5910
5911  minor changes to put "TZif" at the start of each timezone information file
5912
5913  a rule has also been added to the Makefile so you can
5914	make zones
5915  to just recompile the zone information files (rather than doing a
5916  full "make install" with its other effects).
5917
5918
5919Release data1997i - 1997-10-07 08:45:38 -0400
5920
5921  changes to Africa by Paul Eggert
5922
5923
5924Release code1997g-data1997h - 1997-09-04 16:56:54 -0400
5925
5926  corrections for Uruguay (and other locations)
5927
5928  Arthur David Olson's simple-minded fix allowing mktime to both
5929  correctly handle leap seconds and correctly handle tm_sec values
5930  upon which arithmetic has been performed.
5931
5932
5933Release code1997f-data1997g - 1997-07-19 13:15:02 -0400
5934
5935  Paul Eggert's updates
5936
5937  a small change to a function prototype;
5938
5939  "Music" has been renamed "Arts.htm", HTMLified, and augmented to
5940  include information on Around the World in Eighty Days.
5941
5942
5943Release code1997e-data1997f - 1997-05-03 18:52:34 -0400
5944
5945  fixes to zic's error handling
5946
5947  changes inspired by the item circulated on Slovenia
5948
5949  The description of Web resources has been HTMLified for browsing
5950  convenience.
5951
5952  A new piece of tz-related music has been added to the "Music" file.
5953
5954
5955Release code1997d-data1997e - 1997-03-29 12:48:52 -0500
5956
5957  Paul Eggert's latest suggestions
5958
5959
5960Release code1997c-data1997d - 1997-03-07 20:37:54 -0500
5961
5962  changes to "zic.c" to correct performance of the "-s" option
5963
5964  a new file "usno1997"
5965
5966
5967Release data1997c - 1997-03-04 09:58:18 -0500
5968
5969  changes in Israel
5970
5971
5972Release 1997b - 1997-02-27 18:34:19 -0500
5973
5974  The data file incorporates the 1997 leap second.
5975
5976  The code file incorporates Arthur David Olson's take on the
5977  zic/multiprocessor/directory-creation situation.
5978
5979
5980Release 1997a - 1997-01-21 09:11:10 -0500
5981
5982  Paul Eggert's Antarctica (and other changes)
5983
5984  Arthur David Olson finessed the "getopt" issue by checking against
5985  both -1 and EOF (regardless of POSIX, SunOS 4.1.1's manual says -1
5986  is returned while SunOS 5.5's manual says EOF is returned).
5987
5988
5989Release code1996o-data1996n - 1996-12-27 21:42:05 -0500
5990
5991  Paul Eggert's latest changes
5992
5993
5994Release code1996n - 1996-12-16 09:42:02 -0500
5995
5996  link snapping fix from Bruce Evans (via Garrett Wollman)
5997
5998
5999Release data1996m - 1996-11-24 02:37:34 -0000
6000  [tzdata1996m.tar.gz is missing!]
6001
6002  Paul Eggert's batch of changes
6003
6004
6005Release code1996m-data1996l - 1996-11-05 14:00:12 -0500
6006
6007  No functional changes here; the files have simply been changed to
6008  make more use of ISO style dates in comments. The names of the above
6009  files now include the year in full.
6010
6011
6012Release code96l - 1996-09-08 17:12:20 -0400
6013
6014  tzcode96k was missing a couple of pieces.
6015
6016
6017Release 96k - 1996-09-08 16:06:22 -0400
6018
6019  the latest round of changes from Paul Eggert
6020
6021  the recent Year 2000 material
6022
6023
6024Release code96j - 1996-07-30 13:18:53 -0400
6025
6026  Set sp->typecnt as suggested by Timothy Patrick Murphy.
6027
6028
6029Release code96i - 1996-07-27 20:11:35 -0400
6030
6031  Paul's suggested patch for strftime %V week numbers
6032
6033
6034Release data96i - 1996-07-01 18:13:04 -0400
6035
6036  "northamerica" and "europe" changes by Paul Eggert
6037
6038
6039Release code96h - 1996-06-05 08:02:21 -0400
6040
6041  fix for handling transitions specified in Universal Time
6042
6043  Some "public domain" notices have also been added.
6044
6045
6046Release code96g - 1996-05-16 14:00:26 -0400
6047
6048  fix for the simultaneous-DST-and-zone-change challenge
6049
6050
6051Release data96h - 1996-05-09 17:40:51 -0400
6052
6053  changes by Paul Eggert
6054
6055
6056Release code96f-data96g - 1996-05-03 03:09:59 -0000
6057  [tzcode96f.tar.gz + tzdata96g.tar.gz are both missing!]
6058
6059  The changes get us some of the way to fixing the problems noted in Paul
6060  Eggert's letter yesterday (in addition to a few others).  The approach
6061  has been to make zic a bit smarter about figuring out what time zone
6062  abbreviations apply just after the time specified in the "UNTIL" part
6063  of a zone line.  Putting the smarts in zic means avoiding having
6064  transition times show up in both "Zone" lines and "Rule" lines, which
6065  in turn avoids multiple transition time entries in time zone files.
6066  (This also makes the zic input files such as "europe" a bit shorter and
6067  should ease maintenance.)
6068
6069
6070Release data96f - 1996-04-19 19:20:03 -0000
6071  [tzdata96f.tar.gz is missing!]
6072
6073  The only changes are to the "northamerica" file; the time zone
6074  abbreviation for Denver is corrected to MST (and MDT), and the
6075  comments for Mexico have been updated.
6076
6077
6078Release data96e - 1996-03-19 17:37:26 -0500
6079
6080  Proposals by Paul Eggert, in particular the Portugal change that
6081  comes into play at the end of this month.
6082
6083
6084Release data96d - 1996-03-18 20:49:39 -0500
6085
6086  [not summarized]
6087
6088
6089Release code96e - 1996-02-29 15:43:27 -0000
6090  [tzcode96e.tar.gz is missing!]
6091
6092  internationalization changes and the fix to the documentation for strftime
6093
6094
6095Release code96d-data96c - 1996-02-12 11:05:27 -0500
6096
6097  The "code" file simply updates Bob Kridle's electronic address.
6098
6099  The "data" file updates rules for Mexico.
6100
6101
6102Release data96b - 1996-01-27 15:44:42 -0500
6103
6104  Kiribati change
6105
6106
6107Release code96c - 1996-01-16 16:58:15 -0500
6108
6109  leap-year streamlining and binary-search changes
6110
6111  fix to newctime.3
6112
6113
6114Release code96b - 1996-01-10 20:42:39 -0500
6115
6116  fixes and enhancements from Paul Eggert, including code that
6117  emulates the behavior of recent versions of the SunOS "date"
6118  command.
6119
6120
6121Release 96a - 1996-01-06 09:08:24 -0500
6122
6123  Israel updates
6124
6125  fixes to strftime.c for correct ISO 8601 week number generation,
6126  plus support for two new formats ('G' and 'g') to give ISO 8601 year
6127  numbers (which are not necessarily the same as calendar year numbers)
6128
6129
6130Release code95i-data95m - 1995-12-21 12:46:47 -0500
6131
6132  The latest revisions from Paul Eggert are included, the usno1995
6133  file has been updated, and a new file ("WWW") covering useful URLs
6134  has been added.
6135
6136
6137Release code95h-data95l - 1995-12-19 18:10:12 -0500
6138
6139  A simplification of a macro definition, a change to data for Sudan,
6140  and (for last minute shoppers) notes in the "Music" file on the CD
6141  "Old Man Time".
6142
6143
6144Release code95g-data95k - 1995-10-30 10:32:47 -0500
6145
6146  (slightly reformatted) 8-bit-clean proposed patch
6147
6148  minor patch: US/Eastern -> America/New_York
6149
6150  snapshot of the USNO's latest data ("usno1995")
6151
6152  some other minor cleanups
6153
6154
6155Release code95f-data95j - 1995-10-28 21:01:34 -0000
6156  [tzcode95f.tar.gz + tzdata95j.tar.gz are both missing!]
6157
6158  European cleanups
6159
6160  support for 64-bit time_t's
6161
6162  optimization in localtime.c
6163
6164
6165Release code95e - 1995-10-13 13:23:57 -0400
6166
6167  the mktime change to scan from future to past when trying to find time zone
6168  offsets
6169
6170
6171Release data95i - 1995-09-26 10:43:26 -0400
6172
6173  For Canada/Central, guess that the Sun customer's "one week too
6174  early" was just a approximation, and the true error is one month
6175  too early.  This is consistent with the rest of Canada.
6176
6177
6178Release data95h - 1995-09-21 11:26:48 -0400
6179
6180  latest changes from Paul Eggert
6181
6182
6183Release code95d - 1995-09-14 11:14:45 -0400
6184
6185  the addition of a "Music" file, which documents four recorded
6186  versions of the tune "Save That Time".
6187
6188
6189Release data95g - 1995-09-01 17:21:36 -0400
6190
6191  "yearistype" correction
6192
6193
6194Release data95f - 1995-08-28 20:46:56 -0400
6195
6196  Paul Eggert's change to the australasia file
6197
6198
6199Release data95e - 1995-07-08 18:02:34 -0400
6200
6201  The only change is a leap second at the end of this year.
6202  Thanks to Bradley White for forwarding news on the leap second.
6203
6204
6205Release data95d - 1995-07-03 13:26:22 -0400
6206
6207  Paul Eggert's changes
6208
6209
6210Release data95c - 1995-07-02 19:19:28 -0400
6211
6212  changes to "asia", "backward", "europe", and "southamerica"
6213  (read: northamericacentrics need not apply)
6214
6215
6216Release code95c - 1995-03-13 14:00:46 -0500
6217
6218  one-line fix for sign extension problems in detzcode
6219
6220
6221Release 95b - 1995-03-04 11:22:38 -0500
6222
6223  Minor changes in both:
6224
6225  The "code" file contains a workaround for the lack of "unistd.h" in
6226  Microsoft C++ version 7.
6227
6228  The "data" file contains a fixed "Link" for America/Shiprock.
6229
6230
6231Release 94h - 1994-12-10 12:51:14 -0500
6232
6233  The files:
6234
6235  *	incorporate the changes to "zdump" and "date" to make changes to
6236	the "TZ" environment variable permanent;
6237
6238  *	incorporate the table changes by Paul Eggert;
6239
6240  *	include (and document) support for universal time specifications in
6241	data files - but do not (yet) include use of this feature in the
6242	data files.
6243
6244  Think of this as "TZ Classic" - the software has been set up not to break if
6245  universal time shows up in its input, and data entries have been
6246  left as is so as not to break existing implementations.
6247
6248
6249Release data94f - 1994-08-20 12:56:09 -0400
6250
6251  (with thanks!) the latest data updates from Paul Eggert
6252
6253
6254Release data94e - 1994-06-04 13:13:53 -0400
6255
6256  [not summarized]
6257
6258
6259Release code94g - 1994-05-05 12:14:07 -0400
6260
6261  fix missing "optind.c" and a reference to it in the Makefile
6262
6263
6264Release code94f - 1994-05-05 13:00:33 -0000
6265  [tzcode94f.tar.gz is missing!]
6266
6267  changes to avoid overflow in difftime, as well as changes to cope
6268  with the 52/53 challenge in strftime
6269
6270
6271Release code94e - 1994-03-30 23:32:59 -0500
6272
6273  change for the benefit of PCTS
6274
6275
6276Release 94d - 1994-02-24 15:42:25 -0500
6277
6278  Avoid clashes with POSIX semantics for zones such as GMT+4.
6279
6280  Some other very minor housekeeping is also present.
6281
6282
6283Release code94c - 1994-02-10 08:52:40 -0500
6284
6285  Fix bug where mkdirs was broken unless you compile with
6286  -fwritable-strings (which is generally losing to do).
6287
6288
6289Release 94b - 1994-02-07 10:04:33 -0500
6290
6291  work by Paul Eggert who notes:
6292
6293  I found another book of time zone histories by E W Whitman; it's not
6294  as extensive as Shanks but has a few goodies of its own.  I used it
6295  to update the tables.  I also fixed some more as a result of
6296  correspondence with Adam David and Peter Ilieve, and move some stray
6297  links from 'europe' to 'backward'.  I corrected some scanning errors
6298  in usno1989.
6299
6300  As far as the code goes, I fixed zic to allow years in the range
6301  INT_MIN to INT_MAX; this fixed a few boundary conditions around 1900.
6302  And I cleaned up the zic documentation a little bit.
6303
6304
6305Release data94a - 1994-02-03 08:58:54 -0500
6306
6307  It simply incorporates the recently announced leap second into the
6308  "leapseconds" file.
6309
6310
6311Release 93g - 1993-11-22 17:28:27 -0500
6312
6313  Paul Eggert has provided a good deal of historic information (based
6314  on Shanks), and there are some code changes to deal with the buglets
6315  that crawled out in dealing with the new information.
6316
6317
6318Release 93f - 1993-10-15 12:27:46 -0400
6319
6320  Paul Eggert's changes
6321
6322
6323Release 93e - 1993-09-05 21:21:44 -0400
6324
6325  This has updated data for Israel, England, and Kwajalein.  There's
6326  also an update to "zdump" to cope with Kwajalein's 24-hour jump.
6327  Thanks to Paul Eggert and Peter Ilieve for the changes.
6328
6329
6330Release 93d - 1993-06-17 23:34:17 -0400
6331
6332  new fix and new data on Israel
6333
6334
6335Release 93c - 1993-06-06 19:31:55 -0400
6336
6337  [not summarized]
6338
6339
6340Release 93b - 1993-02-02 14:53:58 -0500
6341
6342  updated "leapseconds" file
6343
6344
6345Release 93 - 1993-01-08 07:01:06 -0500
6346
6347  At kre's suggestion, the package has been split in two - a code piece
6348  (which also includes documentation) that's only of use to folks who
6349  want to recompile things and a data piece useful to anyone who can
6350  run "zic".
6351
6352  The new version has a few changes to the data files, a few
6353  portability changes, and an off-by-one fix (with thanks to
6354  Tom Karzes at deshaw.com for providing a description and a
6355  solution).
6356
6357
6358Release 92c - 1992-11-21 17:35:36 -0000
6359  [tz92c.tar.Z is missing!]
6360
6361  The fallout from the latest round of DST transitions.
6362
6363  There are changes for Portugal, Saskatchewan, and "Pacific-New";
6364  there's also a change to "zic.c" that makes it portable to more systems.
6365
6366
6367Release 92 - 1992-04-25 18:17:03 -0000
6368  [tz92.tar.Z is missing!]
6369
6370  By popular demand (well, at any rate, following a request by kre at munnari)
6371
6372
6373The 1989 update of the time zone package featured:
6374
6375  *	POSIXization (including interpretation of POSIX-style TZ environment
6376	variables, provided by Guy Harris),
6377  *	ANSIfication (including versions of "mktime" and "difftime"),
6378  *	SVIDulation (an "altzone" variable)
6379  *	MACHination (the "gtime" function)
6380  *	corrections to some time zone data (including corrections to the rules
6381	for Great Britain and New Zealand)
6382  *	reference data from the United States Naval Observatory for folks who
6383	want to do additional time zones
6384  *	and the 1989 data for Saudi Arabia.
6385
6386  (Since this code will be treated as "part of the implementation" in some
6387  places and as "part of the application" in others, there's no good way to
6388  name functions, such as timegm, that are not part of the proposed ANSI C
6389  standard; such functions have kept their old, underscore-free names in this
6390  update.)
6391
6392  And the "dysize" function has disappeared; it was present to allow
6393  compilation of the "date" command on old BSD systems, and a version of "date"
6394  is now provided in the package.  The "date" command is not created when you
6395  "make all" since it may lack options provided by the version distributed with
6396  your operating system, or may not interact with the system in the same way
6397  the native version does.
6398
6399  Since POSIX frowns on correct leap second handling, the default behavior of
6400  the "zic" command (in the absence of a "-L" option) has been changed to omit
6401  leap second information from its output files.
6402
6403
6404-----
6405Notes
6406
6407This file contains copies of the part of each release announcement
6408that talks about the changes in that release.  The text has been
6409adapted and reformatted for the purposes of this file.
6410
6411Traditionally a release R consists of a pair of tarball files,
6412tzcodeR.tar.gz and tzdataR.tar.gz.  However, some releases (e.g.,
6413code2010a, data2012c) consist of just one or the other tarball, and a
6414few (e.g., code2012c-data2012d) have tarballs with mixed version
6415numbers.  Recent releases also come in an experimental format
6416consisting of a single tarball tzdb-R.tar.lz with extra data.
6417
6418Release timestamps are taken from the release's commit (for newer,
6419Git-based releases), from the newest file in the tarball (for older
6420releases, where this info is available) or from the email announcing
6421the release (if all else fails; these are marked with a time zone
6422abbreviation of -0000 and an "is missing!" comment).
6423
6424Earlier versions of the code and data were not announced on the tz
6425list and are not summarized here.
6426
6427This file is in the public domain.
6428
6429Local Variables:
6430coding: utf-8
6431End:
6432