NEWS revision 1.47
1News for the tz database
2
3Release 2025b - 2025-03-22 13:40:46 -0700
4
5  Briefly:
6    New zone for Aysén Region in Chile which moves from -04/-03 to -03.
7
8  Changes to future timestamps
9
10    Chile's Aysén Region moves from -04/-03 to -03 year-round, joining
11    Magallanes Region.  The region will not change its clocks on
12    2025-04-05 at 24:00, diverging from America/Santiago and creating a
13    new zone America/Coyhaique.  (Thanks to Yonathan Dossow.)  Model
14    this as a change to standard offset effective 2025-03-20.
15
16  Changes to past timestamps
17
18    Iran switched from +04 to +0330 on 1978-11-10 at 24:00, not at
19    year end.  (Thanks to Roozbeh Pournader.)
20
21  Changes to code
22
23    'zic -l TIMEZONE -d . -l /some/other/file/system' no longer
24    attempts to create an incorrect symlink, and no longer has a
25    read buffer underflow.  (Problem reported by Evgeniy Gorbanev.)
26
27
28Release 2025a - 2025-01-15 10:47:24 -0800
29
30  Briefly:
31    Paraguay adopted permanent -03 starting spring 2024.
32    Improve pre-1991 data for the Philippines.
33    Etc/Unknown is now reserved.
34
35  Changes to future timestamps
36
37    Paraguay stopped changing its clocks after the spring-forward
38    transition on 2024-10-06, so it is now permanently at -03.
39    (Thanks to Heitor David Pinto and Even Scharning.)
40    This affects timestamps starting 2025-03-22, as well as the
41    obsolescent tm_isdst flags starting 2024-10-15.
42
43  Changes to past timestamps
44
45    Correct timestamps for the Philippines before 1900, and from 1937
46    through 1990.  (Thanks to P Chan for the heads-up and citations.)
47    This includes adjusting local mean time before 1899; fixing
48    transitions in September 1899, January 1937, and June 1954; adding
49    transitions in December 1941, November 1945, March and September
50    1977, and May and July 1990; and removing incorrect transitions in
51    March and September 1978.
52
53  Changes to data
54
55    Add zone1970.tab lines for the Concordia and Eyre Bird Observatory
56    research stations.  (Thanks to Derick Rethans and Jule Dabars.)
57
58  Changes to code
59
60    strftime %s now generates the correct numeric string even when the
61    represented number does not fit into time_t.  This is better than
62    generating the numeric equivalent of (time_t) -1, as strftime did
63    in TZDB releases 96a (when %s was introduced) through 2020a and in
64    releases 2022b through 2024b.  It is also better than failing and
65    returning 0, as strftime did in releases 2020b through 2022a.
66
67    strftime now outputs an invalid conversion specifier as-is,
68    instead of eliding the leading '%', which confused debugging.
69
70    An invalid TZ now generates the time zone abbreviation "-00", not
71    "UTC", to help the user see that an error has occurred.  (Thanks
72    to Arthur David Olson for suggesting a "wrong result".)
73
74    mktime and timeoff no longer incorrectly fail merely because a
75    struct tm component near INT_MIN or INT_MAX overflows when a
76    lower-order component carries into it.
77
78    TZNAME_MAXIMUM, the maximum number of bytes in a proleptic TZ
79    string's time zone abbreviation, now defaults to 254 not 255.
80    This helps reduce the size of internal state from 25480 to 21384
81    on common platforms.  This change should not be a problem, as
82    nobody uses such long "abbreviations" and the longstanding tzcode
83    maximum was 16 until release 2023a.  For those who prefer no
84    arbitrary limits, you can now specify TZNAME_MAXIMUM values up to
85    PTRDIFF_MAX, a limit forced by C anyway; formerly tzcode silently
86    misbehaved unless TZNAME_MAXIMUM was less than INT_MAX.
87
88    tzset and related functions no longer leak a file descriptor if
89    another thread forks or execs at about the same time and if the
90    platform has O_CLOFORK and O_CLOEXEC respectively.  Also, the
91    functions no longer let a TZif file become a controlling terminal.
92
93    'zdump -' now reads TZif data from /dev/stdin.
94    (From a question by Arthur David Olson.)
95
96  Changes to documentation
97
98    The name Etc/Unknown is now reserved: it will not be used by TZDB.
99    This is for compatibility with CLDR, which uses the string
100    "Etc/Unknown" for an unknown or invalid timezone.  (Thanks to
101    Justin Grant, Mark Davis, and Guy Harris.)
102
103    Cite Internet RFC 9636, which obsoletes RFC 8536 for TZif format.
104
105
106Release 2024b - 2024-09-04 12:27:47 -0700
107
108  Briefly:
109    Improve historical data for Mexico, Mongolia, and Portugal.
110    System V names are now obsolescent.
111    The main data form now uses %z.
112    The code now conforms to RFC 8536 for early timestamps.
113    Support POSIX.1-2024, which removes asctime_r and ctime_r.
114    Assume POSIX.2-1992 or later for shell scripts.
115    SUPPORT_C89 now defaults to 1.
116
117  Changes to past timestamps
118
119    Asia/Choibalsan is now an alias for Asia/Ulaanbaatar rather than
120    being a separate Zone with differing behavior before April 2008.
121    This seems better given our wildly conflicting information about
122    Mongolia's time zone history.  (Thanks to Heitor David Pinto.)
123
124    Historical transitions for Mexico have been updated based on
125    official Mexican decrees.  The affected timestamps occur during
126    the years 1921-1927, 1931, 1945, 1949-1970, and 1981-1997.
127    The affected zones are America/Bahia_Banderas, America/Cancun,
128    America/Chihuahua, America/Ciudad_Juarez, America/Hermosillo,
129    America/Mazatlan, America/Merida, America/Mexico_City,
130    America/Monterrey, America/Ojinaga, and America/Tijuana.
131    (Thanks to Heitor David Pinto.)
132
133    Historical transitions for Portugal, represented by Europe/Lisbon,
134    Atlantic/Azores, and Atlantic/Madeira, have been updated based on a
135    close reading of old Portuguese legislation, replacing previous data
136    mainly originating from Whitman and Shanks & Pottenger.  These
137    changes affect a few transitions in 1917-1921, 1924, and 1940
138    throughout these regions by a few hours or days, and various
139    timestamps between 1977 and 1993 depending on the region.  In
140    particular, the Azores and Madeira did not observe DST from 1977 to
141    1981.  Additionally, the adoption of standard zonal time in former
142    Portuguese colonies have been adjusted: Africa/Maputo in 1909, and
143    Asia/Dili by 22 minutes at the start of 1912.
144    (Thanks to Tim Parenti.)
145
146  Changes to past tm_isdst flags
147
148    The period from 1966-04-03 through 1966-10-02 in Portugal is now
149    modeled as DST, to more closely reflect how contemporaneous changes
150    in law entered into force.
151
152  Changes to data
153
154    Names present only for compatibility with UNIX System V
155    (last released in the 1990s) have been moved to 'backward'.
156    These names, which for post-1970 timestamps mostly just duplicate
157    data of geographical names, were confusing downstream uses.
158    Names moved to 'backward' are now links to geographical names.
159    This affects behavior for TZ='EET' for some pre-1981 timestamps,
160    for TZ='CET' for some pre-1947 timestamps, and for TZ='WET' for
161    some pre-1996 timestamps.  Also, TZ='MET' now behaves like
162    TZ='CET' and so uses the abbreviation "CET" rather than "MET".
163    Those needing the previous TZDB behavior, which does not match any
164    real-world clocks, can find the old entries in 'backzone'.
165    (Problem reported by Justin Grant.)
166
167    The main source files' time zone abbreviations now use %z,
168    supported by zic since release 2015f and used in vanguard form
169    since release 2022b.  For example, America/Sao_Paulo now contains
170    the zone continuation line "-3:00 Brazil %z", which is less error
171    prone than the old "-3:00 Brazil -03/-02".  This does not change
172    the represented data: the generated TZif files are unchanged.
173    Rearguard form still avoids %z, to support obsolescent parsers.
174
175    Asia/Almaty has been removed from zonenow.tab as it now agrees
176    with Asia/Tashkent for future timestamps, due to Kazakhstan's
177    2024-02-29 time zone change.  Similarly, America/Scoresbysund
178    has been removed, as it now agrees with America/Nuuk due to
179    its 2024-03-31 time zone change.
180
181  Changes to code
182
183    localtime.c now always uses a TZif file's time type 0 to handle
184    timestamps before the file's first transition.  Formerly,
185    localtime.c sometimes inferred a different time type, in order to
186    handle problematic data generated by zic 2018e or earlier.  As it
187    is now safe to assume more recent versions of zic, there is no
188    longer a pressing need to fail to conform RFC 8536 section 3.2,
189    which requires using time type 0 in this situation.  This change
190    does not affect behavior when reading TZif files generated by zic
191    2018f and later.
192
193    POSIX.1-2024 removes asctime_r and ctime_r and does not let
194    libraries define them, so remove them except when needed to
195    conform to earlier POSIX.  These functions are dangerous as they
196    can overrun user buffers.  If you still need them, add
197    -DSUPPORT_POSIX2008 to CFLAGS.
198
199    The SUPPORT_C89 option now defaults to 1 instead of 0, fixing a
200    POSIX-conformance bug introduced in 2023a.
201
202    tzselect now supports POSIX.1-2024 proleptic TZ strings.  Also, it
203    assumes POSIX.2-1992 or later, as practical porting targets now
204    all support that, and it uses some features from POSIX.1-2024 if
205    available.
206
207  Changes to build procedure
208
209    'make check' no longer requires curl and Internet access.
210
211    The build procedure now assumes POSIX.2-1992 or later, to simplify
212    maintenance.  To build on Solaris 10, the only extant system still
213    defaulting to pre-POSIX, prepend /usr/xpg4/bin to PATH.
214
215  Changes to documentation
216
217    The documentation now reflects POSIX.1-2024.
218
219  Changes to commentary
220
221    Commentary about historical transitions in Portugal and her former
222    colonies has been expanded with links to relevant legislation.
223    (Thanks to Tim Parenti.)
224
225
226Release 2024a - 2024-02-01 09:28:56 -0800
227
228  Briefly:
229    Kazakhstan unifies on UTC+5 beginning 2024-03-01.
230    Palestine springs forward a week later after Ramadan.
231    zic no longer pretends to support indefinite-past DST.
232    localtime no longer mishandles Ciudad Juárez in 2422.
233
234  Changes to future timestamps
235
236    Kazakhstan unifies on UTC+5.  This affects Asia/Almaty and
237    Asia/Qostanay which together represent the eastern portion of the
238    country that will transition from UTC+6 on 2024-03-01 at 00:00 to
239    join the western portion.  (Thanks to Zhanbolat Raimbekov.)
240
241    Palestine springs forward a week later than previously predicted
242    in 2024 and 2025.  (Thanks to Heba Hamad.)  Change spring-forward
243    predictions to the second Saturday after Ramadan, not the first;
244    this also affects other predictions starting in 2039.
245
246  Changes to past timestamps
247
248    Asia/Ho_Chi_Minh's 1955-07-01 transition occurred at 01:00
249    not 00:00.  (Thanks to Đoàn Trần Công Danh.)
250
251    From 1947 through 1949, Toronto's transitions occurred at 02:00
252    not 00:00.  (Thanks to Chris Walton.)
253
254    In 1911 Miquelon adopted standard time on June 15, not May 15.
255
256  Changes to code
257
258    The FROM and TO columns of Rule lines can no longer be "minimum"
259    or an abbreviation of "minimum", because TZif files do not support
260    DST rules that extend into the indefinite past - although these
261    rules were supported when TZif files had only 32-bit data, this
262    stopped working when 64-bit TZif files were introduced in 1995.
263    This should not be a problem for realistic data, since DST was
264    first used in the 20th century.  As a transition aid, FROM columns
265    like "minimum" are now diagnosed and then treated as if they were
266    the year 1900; this should suffice for TZif files on old systems
267    with only 32-bit time_t, and it is more compatible with bugs in
268    2023c-and-earlier localtime.c.  (Problem reported by Yoshito
269    Umaoka.)
270
271    localtime and related functions no longer mishandle some
272    timestamps that occur about 400 years after a switch to a time
273    zone with a DST schedule.  In 2023d data this problem was visible
274    for some timestamps in November 2422, November 2822, etc. in
275    America/Ciudad_Juarez.  (Problem reported by Gilmore Davidson.)
276
277    strftime %s now uses tm_gmtoff if available.  (Problem and draft
278    patch reported by Dag-Erling Smørgrav.)
279
280  Changes to build procedure
281
282    The leap-seconds.list file is now copied from the IERS instead of
283    from its downstream counterpart at NIST, as the IERS version is
284    now in the public domain too and tends to be more up-to-date.
285    (Thanks to Martin Burnicki for liaisoning with the IERS.)
286
287  Changes to documentation
288
289    The strftime man page documents which struct tm members affect
290    which conversion specs, and that tzset is called.  (Problems
291    reported by Robert Elz and Steve Summit.)
292
293
294Release 2023d - 2023-12-21 20:02:24 -0800
295
296  Briefly:
297    Ittoqqortoormiit, Greenland changes time zones on 2024-03-31.
298    Vostok, Antarctica changed time zones on 2023-12-18.
299    Casey, Antarctica changed time zones five times since 2020.
300    Code and data fixes for Palestine timestamps starting in 2072.
301    A new data file zonenow.tab for timestamps starting now.
302
303  Changes to future timestamps
304
305    Ittoqqortoormiit, Greenland (America/Scoresbysund) joins most of
306    the rest of Greenland's timekeeping practice on 2024-03-31, by
307    changing its time zone from -01/+00 to -02/-01 at the same moment
308    as the spring-forward transition.  Its clocks will therefore not
309    spring forward as previously scheduled.  The time zone change
310    reverts to its common practice before 1981.  (Thanks to Jule Dabars.)
311
312    Fix predictions for DST transitions in Palestine in 2072-2075,
313    correcting a typo introduced in 2023a.  (Thanks to Jule Dabars.)
314
315  Changes to past and future timestamps
316
317    Vostok, Antarctica changed to +05 on 2023-12-18.  It had been at
318    +07 (not +06) for years.  (Thanks to Zakhary V. Akulov.)
319
320    Change data for Casey, Antarctica to agree with timeanddate.com,
321    by adding five time zone changes since 2020.  Casey is now at +08
322    instead of +11.
323
324  Changes to past tm_isdst flags
325
326    Much of Greenland, represented by America/Nuuk, changed its
327    standard time from -03 to -02 on 2023-03-25, not on 2023-10-28.
328    This does not affect UTC offsets, only the tm_isdst flag.
329    (Thanks to Thomas M. Steenholdt.)
330
331  New data file
332
333    A new data file zonenow.tab helps configure applications that use
334    timestamps dated from now on.  This simplifies configuration,
335    since users choose from a smaller Zone set.  The file's format is
336    experimental and subject to change.
337
338  Changes to code
339
340    localtime.c no longer mishandles TZif files that contain a single
341    transition into a DST regime.  Previously, it incorrectly assumed
342    DST was in effect before the transition too.  (Thanks to Alois
343    Treindl for debugging help.)
344
345    localtime.c's timeoff no longer collides with OpenBSD 7.4.
346
347    The C code now uses _Generic only if __STDC_VERSION__ says the
348    compiler is C11 or later.
349
350    tzselect now optionally reads zonenow.tab, to simplify when
351    configuring only for timestamps dated from now on.
352
353    tzselect no longer creates temporary files.
354
355    tzselect no longer mishandles the following:
356
357      Spaces and most other special characters in BUGEMAIL, PACKAGE,
358      TZDIR, and VERSION.
359
360      TZ strings when using mawk 1.4.3, which mishandles regular
361      expressions of the form /X{2,}/.
362
363      ISO 6709 coordinates when using an awk that lacks the GNU
364      extension of newlines in -v option-arguments.
365
366      Non UTF-8 locales when using an iconv command that lacks the GNU
367      //TRANSLIT extension.
368
369    zic no longer mishandles data for Palestine after the year 2075.
370    Previously, it incorrectly omitted post-2075 transitions that are
371    predicted for just before and just after Ramadan.  (Thanks to Ken
372    Murchison for debugging help.)
373
374    zic now works again on Linux 2.6.16 and 2.6.17 (2006).
375    (Problem reported by Rune Torgersen.)
376
377  Changes to build procedure
378
379    The Makefile is now more compatible with POSIX:
380     * It no longer defines AR, CC, CFLAGS, LDFLAGS, and SHELL.
381     * It no longer uses its own 'cc' in place of CC.
382     * It now uses ARFLAGS, with default specified by POSIX.
383     * It does not use LFLAGS incompatibly with POSIX.
384     * It uses the special .POSIX target.
385     * It quotes special characters more carefully.
386     * It no longer mishandles builds in an ISO 8859 locale.
387    Due to the CC changes, TZDIR is now #defined in a file tzdir.h
388    built by 'make', not in a $(CC) -D option.  Also, TZDEFAULT is
389    now treated like TZDIR as they have similar roles.
390
391  Changes to commentary
392
393     Limitations and hazards of the optional support for obsolescent
394     C89 platforms are documented better, along with a tentative
395     schedule for removing this support.
396
397
398Release 2023c - 2023-03-28 12:42:14 -0700
399
400  Changes to past and future timestamps
401
402    Model Lebanon's DST chaos by reverting data to tzdb 2023a.
403    (Thanks to Rany Hany for the heads-up.)
404
405
406Release 2023b - 2023-03-23 19:50:38 -0700
407
408  Changes to future timestamps
409
410    This year Lebanon springs forward April 20/21 not March 25/26.
411    (Thanks to Saadallah Itani.)  [This was reverted in 2023c.]
412
413
414Release 2023a - 2023-03-22 12:39:33 -0700
415
416  Briefly:
417    Egypt now uses DST again, from April through October.
418    This year Morocco springs forward April 23, not April 30.
419    Palestine delays the start of DST this year.
420    Much of Greenland still uses DST from 2024 on.
421    America/Yellowknife now links to America/Edmonton.
422    tzselect can now use current time to help infer timezone.
423    The code now defaults to C99 or later.
424    Fix use of C23 attributes.
425
426  Changes to future timestamps
427
428    Starting in 2023, Egypt will observe DST from April's last Friday
429    through October's last Thursday.  (Thanks to Ahmad ElDardiry.)
430    Assume the transition times are 00:00 and 24:00, respectively.
431
432    In 2023 Morocco's spring-forward transition after Ramadan
433    will occur April 23, not April 30.  (Thanks to Milamber.)
434    Adjust predictions for future years accordingly.  This affects
435    predictions for 2023, 2031, 2038, and later years.
436
437    This year Palestine will delay its spring forward from
438    March 25 to April 29 due to Ramadan.  (Thanks to Heba Hamad.)
439    Make guesses for future Ramadans too.
440
441    Much of Greenland, represented by America/Nuuk, will continue to
442    observe DST using European Union rules.  When combined with
443    Greenland's decision not to change the clocks in fall 2023,
444    America/Nuuk therefore changes from -03/-02 to -02/-01 effective
445    2023-10-29 at 01:00 UTC.  (Thanks to Thomas M. Steenholdt.)
446    This change from 2022g doesn't affect timestamps until 2024-03-30,
447    and doesn't affect tm_isdst until 2023-03-25.
448
449  Changes to past timestamps
450
451    America/Yellowknife has changed from a Zone to a backward
452    compatibility Link, as it no longer differs from America/Edmonton
453    since 1970.  (Thanks to Almaz Mingaleev.)  This affects some
454    pre-1948 timestamps.  The old data are now in 'backzone'.
455
456  Changes to past time zone abbreviations
457
458    When observing Moscow time, Europe/Kirov and Europe/Volgograd now
459    use the abbreviations MSK/MSD instead of numeric abbreviations,
460    for consistency with other timezones observing Moscow time.
461
462  Changes to code
463
464    You can now tell tzselect local time, to simplify later choices.
465    Select the 'time' option in its first prompt.
466
467    You can now compile with -DTZNAME_MAXIMUM=N to limit time zone
468    abbreviations to N bytes (default 255).  The reference runtime
469    library now rejects POSIX-style TZ strings that contain longer
470    abbreviations, treating them as UTC.  Previously the limit was
471    platform dependent and abbreviations were silently truncated to
472    16 bytes even when the limit was greater than 16.
473
474    The code by default is now designed for C99 or later.  To build on
475    a mostly-C89 platform, compile with -DPORT_TO_C89; this should
476    work on C89 platforms that also support C99 'long long' and
477    perhaps a few other extensions to C89.  To support C89 callers of
478    tzcode's library, compile with -DSUPPORT_C89; however, this could
479    trigger latent bugs in C99-or-later callers.  The two new macros
480    are transitional aids planned to be removed in a future version
481    (say, in 2029), when C99 or later will be required.
482
483    The code now builds again on pre-C99 platforms, if you compile
484    with -DPORT_TO_C89.  This fixes a bug introduced in 2022f.
485
486    On C23-compatible platforms tzcode no longer uses syntax like
487    'static [[noreturn]] void usage(void);'.  Instead, it uses
488    '[[noreturn]] static void usage(void);' as strict C23 requires.
489    (Problem reported by Houge Langley.)
490
491    The code's functions now constrain their arguments with the C
492    'restrict' keyword consistently with their documentation.
493    This may allow future optimizations.
494
495    zdump again builds standalone with ckdadd and without setenv,
496    fixing a bug introduced in 2022g.  (Problem reported by panic.)
497
498    leapseconds.awk can now process a leap seconds file that never
499    expires; this might be useful if leap seconds are discontinued.
500
501  Changes to commentary
502
503    tz-link.html has a new section "Coordinating with governments and
504    distributors".  (Thanks to Neil Fuller for some of the text.)
505
506    To improve tzselect diagnostics, zone1970.tab's comments column is
507    now limited to countries that have multiple timezones.
508
509    Note that there are plans to discontinue leap seconds by 2035.
510
511
512Release 2022g - 2022-11-29 08:58:31 -0800
513
514  Briefly:
515    The northern edge of Chihuahua changes to US timekeeping.
516    Much of Greenland stops changing clocks after March 2023.
517    Fix some pre-1996 timestamps in northern Canada.
518    C89 is now deprecated; please use C99 or later.
519    Portability fixes for AIX, libintl, MS-Windows, musl, z/OS
520    In C code, use more C23 features if available.
521    C23 timegm now supported by default
522    Fixes for unlikely integer overflows
523
524  Changes to future timestamps
525
526    In the Mexican state of Chihuahua, the border strip near the US
527    will change to agree with nearby US locations on 2022-11-30.
528    The strip's western part, represented by Ciudad Juárez, switches
529    from -06 all year to -07/-06 with US DST rules, like El Paso, TX.
530    The eastern part, represented by Ojinaga, will observe US DST next
531    year, like Presidio, TX.  (Thanks to Heitor David Pinto.)
532    A new Zone America/Ciudad_Juarez splits from America/Ojinaga.
533
534    Much of Greenland, represented by America/Nuuk, stops observing
535    winter time after March 2023, so its daylight saving time becomes
536    standard time.  (Thanks to Jonas Nyrup and Jürgen Appel.)
537
538  Changes to past timestamps
539
540    Changes for pre-1996 northern Canada (thanks to Chris Walton):
541
542      Merge America/Iqaluit and America/Pangnirtung into the former,
543      with a backward compatibility link for the latter name.
544      There is no good evidence the two locations differ since 1970.
545      This change affects pre-1996 America/Pangnirtung timestamps.
546
547      Cambridge Bay, Inuvik, Iqaluit, Rankin Inlet, Resolute and
548      Yellowknife did not observe DST in 1965, and did observe DST
549      from 1972 through 1979.
550
551      Whitehorse moved from -09 to -08 on 1966-02-27, not 1967-05-28.
552
553    Colombia's 1993 fallback was 02-06 24:00, not 04-04 00:00.
554    (Thanks to Alois Treindl.)
555
556    Singapore's 1981-12-31 change was at 16:00 UTC (23:30 local time),
557    not 24:00 local time.  (Thanks to Geoff Clare via Robert Elz.)
558
559  Changes to code
560
561    Although tzcode still works with C89, bugs found in recent routine
562    maintenance indicate that bitrot has set in and that in practice
563    C89 is no longer used to build tzcode.  As it is a maintenance
564    burden, support for C89 is planned to be removed soon.  Instead,
565    please use compilers compatible with C99, C11, C17, or C23.
566
567    timegm, which tzcode implemented in 1989, will finally be
568    standardized 34 years later as part of C23, so timegm is now
569    supported even if STD_INSPIRED is not defined.
570
571    Fix bug in zdump's tzalloc emulation on hosts that lack tm_zone.
572    (Problem reported by Đoàn Trần Công Danh.)
573
574    Fix bug in zic on hosts where malloc(0) yields NULL on success.
575    (Problem reported by Tim McBrayer for AIX 6.1.)
576
577    Fix zic configuration to avoid linkage failures on some platforms.
578    (Problems reported by Gilmore Davidson and Igor Ivanov.)
579
580    Work around MS-Windows nmake incompatibility with POSIX.
581    (Problem reported by Manuela Friedrich.)
582
583    Port mktime and strftime to debugging platforms where accessing
584    uninitialized data has undefined behavior (strftime problem
585    reported by Robert Elz).
586
587    Check more carefully for unlikely integer overflows, preferring
588    C23 <stdckdint.h> to overflow checking by hand, as the latter has
589    had obscure bugs.
590
591  Changes to build procedure
592
593    New Makefile rule check_mild that skips checking whether Link
594    lines are in the file 'backward'.  (Inspired by a suggestion from
595    Stephen Colebourne.)
596
597    On C23-compatible platforms tzcode no longer uses syntax like
598    'static [[noreturn]] void usage(void);'.  Instead, it uses
599    '[[noreturn]] static void usage(void);' as strict C23 requires.
600    (Problem reported by Houge Langley.)
601
602
603Release 2022f - 2022-10-28 18:04:57 -0700
604
605  Briefly:
606    Mexico will no longer observe DST except near the US border.
607    Chihuahua moves to year-round -06 on 2022-10-30.
608    Fiji no longer observes DST.
609    Move links to 'backward'.
610    In vanguard form, GMT is now a Zone and Etc/GMT a link.
611    zic now supports links to links, and vanguard form uses this.
612    Simplify four Ontario zones.
613    Fix a Y2438 bug when reading TZif data.
614    Enable 64-bit time_t on 32-bit glibc platforms.
615    Omit large-file support when no longer needed.
616    In C code, use some C23 features if available.
617    Remove no-longer-needed workaround for Qt bug 53071.
618
619  Changes to future timestamps
620
621    Mexico will no longer observe DST after 2022, except for areas
622    near the US border that continue to observe US DST rules.
623    On 2022-10-30 at 02:00 the Mexican state of Chihuahua moves
624    from -07 (-06 with DST) to year-round -06, thus not changing
625    its clocks that day.  The new law states that Chihuahua
626    near the US border no longer observes US DST.
627    (Thanks to gera for the heads-up about Chihuahua.)
628
629    Fiji will not observe DST in 2022/3.  (Thanks to Shalvin Narayan.)
630    For now, assume DST is suspended indefinitely.
631
632  Changes to data
633
634    Move links to 'backward' to ease and simplify link maintenance.
635    This affects generated data only if you use 'make BACKWARD='.
636
637    GMT is now a Zone and Etc/GMT a link instead of vice versa,
638    as GMT is needed for leap second support whereas Etc/GMT is not.
639    However, this change exposes a bug in TZUpdater 2.3.2 so it is
640    present only in vanguard form for now.
641
642    Vanguard form now uses links to links, as zic now supports this.
643
644  Changes to past timestamps
645
646    Simplify four Ontario zones, as most of the post-1970 differences
647    seem to have been imaginary.  (Problem reported by Chris Walton.)
648    Move America/Nipigon, America/Rainy_River, and America/Thunder_Bay
649    to 'backzone'; backward-compatibility links still work, albeit
650    with some different timestamps before November 2005.
651
652  Changes to code
653
654    zic now supports links to links regardless of input line order.
655    For example, if Australia/Sydney is a Zone, the lines
656      Link Australia/Canberra Australia/ACT
657      Link Australia/Sydney Australia/Canberra
658    now work correctly, even though the shell commands
659      ln Australia/Canberra Australia/ACT
660      ln Australia/Sydney Australia/Canberra
661    would fail because the first command attempts to use a link
662    Australia/Canberra that does not exist until after the second
663    command is executed.  Previously, zic had unspecified behavior if
664    a Link line's target was another link, and zic often misbehaved if
665    a Link line's target was a later Link line.
666
667    Fix line number in zic's diagnostic for a link to a link.
668
669    Fix a bug that caused localtime to mishandle timestamps starting
670    in the year 2438 when reading data generated by 'zic -b fat' when
671    distant-future DST transitions occur at times given in standard
672    time or in UT, not the usual case of local time.  This occurs when
673    the corresponding .zi Rule lines specify DST transitions with TO
674    columns of 'max' and AT columns that end in 's' or 'u'.  The
675    number 2438 comes from the 32-bit limit in the year 2038, plus the
676    400-year Gregorian cycle.  (Problem reported by Bradley White.)
677
678    On glibc 2.34 and later, which optionally supports 64-bit time_t
679    on platforms like x86 where time_t was traditionally 32 bits,
680    default time_t to 64 instead of 32 bits.  This lets functions like
681    localtime support timestamps after the year 2038, and fixes
682    year-2038 problems in zic when accessing files dated after 2038.
683    To continue to limit time_t to 32 bits on these platforms, use
684    "make CFLAGS='-D_TIME_BITS=32'".
685
686    In C code, do not enable large-file support on platforms like AIX
687    and macOS that no longer need it now that tzcode does not use
688    off_t or related functions like 'stat'.  Large-file support is
689    still enabled by default on GNU/Linux, as it is needed for 64-bit
690    time_t support.
691
692    In C code, prefer C23 keywords to pre-C23 macros for alignof,
693    bool, false, and true.  Also, use the following C23 features if
694    available: __has_include, unreachable.
695
696    zic no longer works around Qt bug 53071, as the relevant Qt
697    releases have been out of support since 2019.  This change affects
698    only fat TZif files, as thin files never had the workaround.
699
700    zdump no longer modifies the environ vector when compiled on
701    platforms lacking tm_zone or when compiled with -DUSE_LTZ=0.
702    This avoid undefined behavior on POSIX platforms.
703
704
705Release 2022e - 2022-10-11 11:13:02 -0700
706
707  Briefly:
708    Jordan and Syria switch from +02/+03 with DST to year-round +03.
709
710  Changes to future timestamps
711
712    Jordan and Syria are abandoning the DST regime and are changing to
713    permanent +03, so they will not fall back from +03 to +02 on
714    2022-10-28.  (Thanks to Steffen Thorsen and Issam Al-Zuwairi.)
715
716  Changes to past timestamps
717
718    On 1922-01-01 Tijuana adopted standard time at 00:00, not 01:00.
719
720  Changes to past time zone abbreviations and DST flags
721
722    The temporary advancement of clocks in central Mexico in summer
723    1931 is now treated as daylight saving time, instead of as two
724    changes to standard time.
725
726
727Release 2022d - 2022-09-23 12:02:57 -0700
728
729  Briefly:
730    Palestine transitions are now Saturdays at 02:00.
731    Simplify three Ukraine zones into one.
732
733  Changes to future timestamps
734
735    Palestine now springs forward and falls back at 02:00 on the
736    first Saturday on or after March 24 and October 24, respectively.
737    This means 2022 falls back 10-29 at 02:00, not 10-28 at 01:00.
738    (Thanks to Heba Hamad.)
739
740  Changes to past timestamps
741
742    Simplify three Ukraine zones to one, since the post-1970
743    differences seem to have been imaginary.  Move Europe/Uzhgorod and
744    Europe/Zaporozhye to 'backzone'; backward-compatibility links
745    still work, albeit with different timestamps before October 1991.
746
747
748Release 2022c - 2022-08-15 17:47:18 -0700
749
750  Briefly:
751    Work around awk bug in FreeBSD, macOS, etc.
752    Improve tzselect on intercontinental Zones.
753
754  Changes to code
755
756    Work around a bug in onetrueawk that broke commands like
757    'make traditional_tarballs' on FreeBSD, macOS, etc.
758    (Problem reported by Deborah Goldsmith.)
759
760    Add code to tzselect that uses experimental structured comments in
761    zone1970.tab to clarify whether Zones like Africa/Abidjan and
762    Europe/Istanbul cross continent or ocean boundaries.
763    (Inspired by a problem reported by Peter Krefting.)
764
765    Fix bug with 'zic -d /a/b/c' when /a is unwritable but the
766    directory /a/b already exists.
767
768    Remove zoneinfo2tdf.pl, as it was unused and triggered false
769    malware alarms on some email servers.
770
771
772Release 2022b - 2022-08-10 15:38:32 -0700
773
774  Briefly:
775    Chile's DST is delayed by a week in September 2022.
776    Iran no longer observes DST after 2022.
777    Rename Europe/Kiev to Europe/Kyiv.
778    New zic -R option
779    Vanguard form now uses %z.
780    Finish moving duplicate-since-1970 zones to 'backzone'.
781    New build option PACKRATLIST
782    New tailored_tarballs target, replacing rearguard_tarballs
783
784  Changes to future timestamps
785
786    Chile's 2022 DST start is delayed from September 4 to September 11.
787    (Thanks to Juan Correa.)
788
789    Iran plans to stop observing DST permanently, after it falls back
790    on 2022-09-21.  (Thanks to Ali Mirjamali.)
791
792  Changes to past timestamps
793
794    Finish moving to 'backzone' the location-based zones whose
795    timestamps since 1970 are duplicates; adjust links accordingly.
796    This change ordinarily affects only pre-1970 timestamps, and with
797    the new PACKRATLIST option it does not affect any timestamps.
798    In this round the affected zones are Antarctica/Vostok,
799    Asia/Brunei, Asia/Kuala_Lumpur, Atlantic/Reykjavik,
800    Europe/Amsterdam, Europe/Copenhagen, Europe/Luxembourg,
801    Europe/Monaco, Europe/Oslo, Europe/Stockholm, Indian/Christmas,
802    Indian/Cocos, Indian/Kerguelen, Indian/Mahe, Indian/Reunion,
803    Pacific/Chuuk, Pacific/Funafuti, Pacific/Majuro, Pacific/Pohnpei,
804    Pacific/Wake and Pacific/Wallis, and the affected links are
805    Arctic/Longyearbyen, Atlantic/Jan_Mayen, Iceland, Pacific/Ponape,
806    Pacific/Truk, and Pacific/Yap.
807
808    From fall 1994 through fall 1995, Shanks wrote that Crimea's
809    DST transitions were at 02:00 standard time, not at 00:00.
810    (Thanks to Michael Deckers.)
811
812    Iran adopted standard time in 1935, not 1946.  In 1977 it observed
813    DST from 03-21 23:00 to 10-20 24:00; its 1978 transitions were on
814    03-24 and 08-05, not 03-20 and 10-20; and its spring 1979
815    transition was on 05-27, not 03-21.
816    (Thanks to Roozbeh Pournader and Francis Santoni.)
817
818    Chile's observance of -04 from 1946-08-29 through 1947-03-31 was
819    considered DST, not standard time.  Santiago and environs had moved
820    their clocks back to rejoin the rest of mainland Chile; put this
821    change at the end of 1946-08-28.  (Thanks to Michael Deckers.)
822
823    Some old, small clock transitions have been removed, as people at
824    the time did not change their clocks.  This affects Asia/Hong_Kong
825    in 1904, Asia/Ho_Chi_Minh in 1906, and Europe/Dublin in 1880.
826
827  Changes to zone name
828
829    Rename Europe/Kiev to Europe/Kyiv, as "Kyiv" is more common in
830    English now.  Spelling of other names in Ukraine has not yet
831    demonstrably changed in common English practice so for now these
832    names retain old spellings, as in other countries (e.g.,
833    Europe/Prague not "Praha", and Europe/Sofia not "Sofiya").
834
835  Changes to code
836
837    zic has a new option '-R @N' to output explicit transitions < N.
838    (Need suggested by Almaz Mingaleev.)
839
840    'zic -r @N' no longer outputs bad data when N < first transition.
841    (Problem introduced in 2021d and reported by Peter Krefting.)
842
843    zic now checks its input for NUL bytes and unterminated lines, and
844    now supports input line lengths up to 2048 (not 512) bytes.
845
846    gmtime and related code now use the abbreviation "UTC" not "GMT".
847    POSIX is being revised to require this.
848
849    When tzset and related functions set vestigial static variables
850    like tzname, they now prefer specified timestamps to unspecified ones.
851    (Problem reported by Almaz Mingaleev.)
852
853    zic no longer complains "can't determine time zone abbreviation to
854    use just after until time" when a transition to a new standard
855    time occurs simultaneously with the first DST fallback transition.
856
857  Changes to build procedure
858
859    Source data in vanguard form now uses the %z notation, introduced
860    in release 2015f.  For example, for America/Sao_Paulo vanguard
861    form contains the zone continuation line "-3:00 Brazil %z", which
862    is simpler and more reliable than the line "-3:00 Brazil -03/-02"
863    used in main and rearguard forms.  The plan is for the main form
864    to use %z eventually; in the meantime maintainers of zi parsers
865    are encouraged to test the parsers on vanguard.zi.
866
867    The Makefile has a new PACKRATLIST option to select a subset of
868    'backzone'.  For example, 'make PACKRATDATA=backzone
869    PACKRATLIST=zone.tab' now generates TZif files identical to those
870    of the global-tz project.
871
872    The Makefile has a new tailored_tarballs target for generating
873    special-purpose tarballs.  It generalizes and replaces the
874    rearguard_tarballs target and related targets and macros, which
875    are now obsolescent.
876
877    'make install' now defaults LOCALTIME to Factory not GMT,
878    which means the default abbreviation is now "-00" not "GMT".
879
880    Remove the posix_packrat target, marked obsolescent in 2016a.
881
882
883Release 2022a - 2022-03-15 23:02:01 -0700
884
885  Briefly:
886    Palestine will spring forward on 2022-03-27, not -03-26.
887    zdump -v now outputs better failure indications.
888    Bug fixes for code that reads corrupted TZif data.
889
890  Changes to future timestamps
891
892    Palestine will spring forward on 2022-03-27, not 2022-03-26.
893    (Thanks to Heba Hamad.)  Predict future transitions for first
894    Sunday >= March 25.  Additionally, predict fallbacks to be the first
895    Friday on or after October 23, not October's last Friday, to be more
896    consistent with recent practice.  The first differing fallback
897    prediction is on 2025-10-24, not 2025-10-31.
898
899  Changes to past timestamps
900
901    From 1992 through spring 1996, Ukraine's DST transitions were at
902    02:00 standard time, not at 01:00 UTC.  (Thanks to Alois Treindl.)
903
904    Chile's Santiago Mean Time and its LMT precursor have been adjusted
905    eastward by 1 second to align with past and present law.
906
907  Changes to commentary
908
909    Add several references for Chile's 1946/1947 transitions, some of
910    which only affected portions of the country.
911
912  Changes to code
913
914    Fix bug when mktime gets confused by truncated TZif files with
915    unspecified local time.  (Problem reported by Almaz Mingaleev.)
916
917    Fix bug when 32-bit time_t code reads malformed 64-bit TZif data.
918    (Problem reported by Christos Zoulas.)
919
920    When reading a version 2 or later TZif file, the TZif reader now
921    validates the version 1 header and data block only enough to skip
922    over them, as recommended by RFC 8536 section 4.  Also, the TZif
923    reader no longer mistakenly attempts to parse a version 1 TZIf
924    file header as a TZ string.
925
926    zdump -v now outputs "(localtime failed)" and "(gmtime failed)"
927    when local time and UT cannot be determined for a timestamp.
928
929  Changes to build procedure
930
931    Distribution tarballs now use standard POSIX.1-1988 ustar format
932    instead of GNU format.  Although the formats are almost identical
933    for these tarballs, ustar headers' magic fields contain "ustar"
934    instead of "ustar ", and their version fields contain "00" instead
935    of " ".  The two formats are planned to diverge more significantly
936    for tzdb releases after 2242-03-16 12:56:31 UTC, when the ustar
937    format becomes obsolete and the tarballs switch to pax format, an
938    extension of ustar.  For details about these formats, please see
939    "pax - portable archive interchange", IEEE Std 1003.1-2017,
940    <https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13>.
941
942
943Release 2021e - 2021-10-21 18:41:00 -0700
944
945  Changes to future timestamps
946
947    Palestine will fall back 10-29 (not 10-30) at 01:00.
948    (Thanks to P Chan and Heba Hemad.)
949
950
951Release 2021d - 2021-10-15 13:48:18 -0700
952
953  Briefly:
954    Fiji suspends DST for the 2021/2022 season.
955    'zic -r' marks unspecified timestamps with "-00".
956
957  Changes to future timestamps
958
959    Fiji will suspend observance of DST for the 2021/2022 season.
960    Assume for now that it will return next year.  (Thanks to Jashneel
961    Kumar and P Chan.)
962
963  Changes to code
964
965    'zic -r' now uses "-00" time zone abbreviations for intervals
966    with UT offsets that are unspecified due to -r truncation.
967    This implements a change in draft Internet RFC 8536bis.
968
969
970Release 2021c - 2021-10-01 14:21:49 -0700
971
972  Briefly:
973    Revert most 2021b changes to 'backward'.
974    Fix 'zic -b fat' bug in pre-1970 32-bit data.
975    Fix two Link line typos.
976    Distribute SECURITY file.
977
978    This release is intended as a bugfix release, to fix compatibility
979    problems and typos reported since 2021b was released.
980
981  Changes to Link directives
982
983    Revert almost all of 2021b's changes to the 'backward' file,
984    by moving Link directives back to where they were in 2021a.
985    Although 'zic' doesn't care which source file contains a Link
986    directive, some downstream uses ran into trouble with the move.
987    (Problem reported by Stephen Colebourne for Joda-Time.)
988
989    Fix typo that linked Atlantic/Jan_Mayen to the wrong location
990    (problem reported by Chris Walton).
991
992    Fix 'backzone' typo that linked America/Virgin to the wrong
993    location (problem reported by Michael Deckers).
994
995  Changes to code
996
997    Fix a bug in 'zic -b fat' that caused old timestamps to be
998    mishandled in 32-bit-only readers (problem reported by Daniel
999    Fischer).
1000
1001  Changes to documentation
1002
1003    Distribute the SECURITY file (problem reported by Andreas Radke).
1004
1005
1006Release 2021b - 2021-09-24 16:23:00 -0700
1007
1008  Briefly:
1009    Jordan now starts DST on February's last Thursday.
1010    Samoa no longer observes DST.
1011    Merge more location-based Zones whose timestamps agree since 1970.
1012    Move some backward-compatibility links to 'backward'.
1013    Rename Pacific/Enderbury to Pacific/Kanton.
1014    Correct many pre-1993 transitions in Malawi, Portugal, etc.
1015    zic now creates each output file or link atomically.
1016    zic -L no longer omits the POSIX TZ string in its output.
1017    zic fixes for truncation and leap second table expiration.
1018    zic now follows POSIX for TZ strings using all-year DST.
1019    Fix some localtime crashes and bugs in obscure cases.
1020    zdump -v now outputs more-useful boundary cases.
1021    tzfile.5 better matches a draft successor to RFC 8536.
1022    A new file SECURITY.
1023
1024    This release is prompted by recent announcements by Jordan and Samoa.
1025    It incorporates many other changes that had accumulated since 2021a.
1026    However, it omits most proposed changes that merged all Zones
1027    agreeing since 1970, as concerns were raised about doing too many of
1028    these changes at once.  It does keeps some of these changes in the
1029    interest of making tzdb more equitable one step at a time; see
1030    "Merge more location-based Zones" below.
1031
1032  Changes to future timestamps
1033
1034    Jordan now starts DST on February's last Thursday.
1035    (Thanks to Steffen Thorsen.)
1036
1037    Samoa no longer observes DST.  (Thanks to Geoffrey D. Bennett.)
1038
1039  Changes to zone name
1040
1041    Rename Pacific/Enderbury to Pacific/Kanton.  When we added
1042    Enderbury in 1993, we did not know that it is uninhabited and that
1043    Kanton (population two dozen) is the only inhabited location in
1044    that timezone.  The old name is now a backward-compatibility link.
1045
1046  Changes to past timestamps
1047
1048    Correct many pre-1993 transitions, fixing entries originally
1049    derived from Shanks, Whitman, and Mundell.  The fixes include:
1050      - Barbados: standard time was introduced in 1911, not 1932; and
1051	DST was observed in 1942-1944
1052      - Cook Islands: In 1899 they switched from east to west of GMT,
1053	celebrating Christmas for two days.  They (and Niue) switched
1054	to standard time in 1952, not 1901.
1055      - Guyana: corrected LMT for Georgetown; the introduction of
1056	standard time in 1911, not 1915; and corrections to 1975 and
1057	1992 transitions
1058      - Kanton: uninhabited before 1937-08-31
1059      - Niue: only observed -11:20 from 1952 through 1964, then went to
1060        -11 instead of -11:30
1061      - Portugal: DST was observed in 1950
1062      - Tonga: corrected LMT; the introduction of standard time in 1945,
1063        not 1901; and corrections to the transition from +12:20 to +13
1064        in 1961, not 1941
1065    Additional fixes to entries in the 'backzone' file include:
1066      - Enderbury: inhabited only 1860/1885 and 1938-03-06/1942-02-09
1067      - The Gambia: 1933 and 1942 transitions
1068      - Malawi: several 1911 through 1925 transitions
1069      - Sierra Leone: several 1913 through 1941 transitions, and DST
1070	was NOT observed in 1957 through 1962
1071    (Thanks to P Chan, Michael Deckers, Alexander Krivenyshev and
1072    Alois Treindl.)
1073
1074    Merge more location-based Zones whose timestamps agree since 1970,
1075    as pre-1970 timestamps are out of scope.  This is part of a
1076    process that has been ongoing since 2013.  This does not affect
1077    post-1970 timestamps, and timezone historians who build with 'make
1078    PACKRATDATA=backzone' should see no changes to pre-1970 timestamps.
1079    When merging, keep the most-populous location's data, and move
1080    data for other locations to 'backzone' with a backward
1081    link in 'backward'.  For example, move America/Creston data to
1082    'backzone' with a link in 'backward' from America/Phoenix because
1083    the two timezones' timestamps agree since 1970; this change
1084    affects some pre-1968 timestamps in America/Creston because
1085    Creston and Phoenix disagreed before 1968.  The affected Zones
1086    are Africa/Accra, America/Atikokan, America/Blanc-Sablon,
1087    America/Creston, America/Curacao, America/Nassau,
1088    America/Port_of_Spain, Antarctica/DumontDUrville, and
1089    Antarctica/Syowa.
1090
1091  Changes to maintenance procedure
1092
1093    The new file SECURITY covers how to report security-related bugs.
1094
1095    Several backward-compatibility links have been moved to the
1096    'backward' file.  These links, which range from Africa/Addis_Ababa
1097    to Pacific/Saipan, are only for compatibility with now-obsolete
1098    guidelines suggesting an entry for every ISO 3166 code.
1099    The intercontinental convenience links Asia/Istanbul and
1100    Europe/Nicosia have also been moved to 'backward'.
1101
1102  Changes to code
1103
1104    zic now creates each output file or link atomically,
1105    possibly by creating a temporary file and then renaming it.
1106    This avoids races where a TZ setting would temporarily stop
1107    working while zic was installing a replacement file or link.
1108
1109    zic -L no longer omits the POSIX TZ string in its output.
1110    Starting with 2020a, zic -L truncated its output according to the
1111    "Expires" directive or "#expires" comment in the leapseconds file.
1112    The resulting TZif files omitted daylight saving transitions after
1113    the leap second table expired, which led to far less accurate
1114    predictions of times after the expiry.  Although future timestamps
1115    cannot be converted accurately in the presence of leap seconds, it
1116    is more accurate to convert near-future timestamps with a few
1117    seconds error than with an hour error, so zic -L no longer
1118    truncates output in this way.
1119
1120    Instead, when zic -L is given the "Expires" directive, it now
1121    outputs the expiration by appending a no-change entry to the leap
1122    second table.  Although this should work well with most TZif
1123    readers, it does not conform to Internet RFC 8536 and some pickier
1124    clients (including tzdb 2017c through 2021a) reject it, so
1125    "Expires" directives are currently disabled by default.  To enable
1126    them, set the EXPIRES_LINE Makefile variable.  If a TZif file uses
1127    this new feature it is marked with a new TZif version number 4,
1128    a format intended to be documented in a successor to RFC 8536.
1129    The old-format "#expires" comments are now treated solely as
1130    comments and have no effect on the TZif files.
1131
1132    zic -L LEAPFILE -r @LO no longer generates an invalid TZif file
1133    that omits leap second information for the range LO..B when LO
1134    falls between two leap seconds A and B.  Instead, it generates a
1135    TZif version 4 file that represents the previously missing
1136    information.
1137
1138    The TZif reader now allows the leap second table to begin with a
1139    correction other than -1 or +1, and to contain adjacent
1140    transitions with equal corrections.  This supports TZif version 4.
1141
1142    The TZif reader now lets leap seconds occur less than 28 days
1143    apart.  This supports possible future TZif extensions.
1144
1145    Fix bug that caused 'localtime' etc. to crash when TZ was
1146    set to a all-year DST string like "EST5EDT4,0/0,J365/25" that does
1147    not conform to POSIX but does conform to Internet RFC 8536.
1148
1149    Fix another bug that caused 'localtime' etc. to crash when TZ was
1150    set to a POSIX-conforming but unusual TZ string like
1151    "EST5EDT4,0/0,J365/0", where almost all the year is DST.
1152
1153    Fix yet another bug that caused 'localtime' etc. to mishandle slim
1154    TZif files containing leap seconds after the last explicit
1155    transition in the table, or when handling far-future timestamps
1156    in slim TZif files lacking leap seconds.
1157
1158    Fix localtime misbehavior involving positive leap seconds.
1159    This change affects only behavior for "right" system time,
1160    which contains leap seconds, and only if the UT offset is
1161    not a multiple of 60 seconds when a positive leap second occurs.
1162    (No such timezone exists in tzdb, luckily.)  Without the fix,
1163    the timestamp was ambiguous during a positive leap second.
1164    With the fix, any seconds occurring after a positive leap second
1165    and within the same localtime minute are counted through 60, not
1166    through 59; their UT offset (tm_gmtoff) is the same as before.
1167    Here is how the fix affects timestamps in a timezone with UT
1168    offset +01:23:45 (5025 seconds) and with a positive leap second at
1169    1972-06-30 23:59:60 UTC (78796800):
1170
1171	time_t    without the fix      with the fix
1172	78796800  1972-07-01 01:23:45  1972-07-01 01:23:45 (leap second)
1173	78796801  1972-07-01 01:23:45  1972-07-01 01:23:46
1174	...
1175	78796815  1972-07-01 01:23:59  1972-07-01 01:23:60
1176	78796816  1972-07-01 01:24:00  1972-07-01 01:24:00
1177
1178    Fix an unlikely bug that caused 'localtime' etc. to misbehave if
1179    civil time changes a few seconds before time_t wraps around, when
1180    leap seconds are enabled.
1181
1182    Fix bug in zic -r; in some cases, the dummy time type after the
1183    last time transition disagreed with the TZ string, contrary to
1184    Internet RFC 8563 section 3.3.
1185
1186    Fix a bug with 'zic -r @X' when X is a negative leap second that
1187    has a nonnegative correction.  Without the fix, the output file
1188    was truncated so that X appeared to be a positive leap second.
1189    Fix a similar, even less likely bug when truncating at a positive
1190    leap second that has a nonpositive correction.
1191
1192    zic -r now reports an error if given rolling leap seconds, as this
1193    usage has never generally worked and is evidently unused.
1194
1195    zic now generates a POSIX-conforming TZ string for TZif files
1196    where all-year DST is predicted for the indefinite future.
1197    For example, for all-year Eastern Daylight Time, zic now generates
1198    "XXX3EDT4,0/0,J365/23" where it previously generated
1199    "EST5EDT,0/0,J365/25" or "".  (Thanks to Michael Deckers for
1200    noting the possibility of POSIX conformance.)
1201
1202    zic.c no longer requires sys/wait.h (thanks to spazmodius for
1203    noting it wasn't needed).
1204
1205    When reading slim TZif files, zdump no longer mishandles leap
1206    seconds on the rare platforms where time_t counts leap seconds,
1207    fixing a bug introduced in 2014g.
1208
1209    zdump -v now outputs timestamps at boundaries of what localtime
1210    and gmtime can represent, instead of the less useful timestamps
1211    one day after the minimum and one day before the maximum.
1212    (Thanks to Arthur David Olson for prototype code, and to Manuela
1213    Friedrich for debugging help.)
1214
1215    zdump's -c and -t options are now consistently inclusive for the
1216    lower time bound and exclusive for the upper.  Formerly they were
1217    inconsistent.  (Confusion noted by Martin Burnicki.)
1218
1219  Changes to build procedure
1220
1221    You can now compile with -DHAVE_MALLOC_ERRNO=0 to port to
1222    non-POSIX hosts where malloc doesn't set errno.
1223    (Problem reported by Jan Engelhardt.)
1224
1225  Changes to documentation
1226
1227    tzfile.5 better matches a draft successor to RFC 8536
1228    <https://datatracker.ietf.org/doc/draft-murchison-rfc8536bis/01/>.
1229
1230
1231Release 2021a - 2021-01-24 10:54:57 -0800
1232
1233  Changes to future timestamps
1234
1235    South Sudan changes from +03 to +02 on 2021-02-01 at 00:00.
1236    (Thanks to Steffen Thorsen.)
1237
1238
1239Release 2020f - 2020-12-29 00:17:46 -0800
1240
1241  Change to build procedure
1242
1243    'make rearguard_tarballs' no longer generates a bad rearguard.zi,
1244    fixing a 2020e bug.  (Problem reported by Deborah Goldsmith.)
1245
1246
1247Release 2020e - 2020-12-22 15:14:34 -0800
1248
1249  Briefly:
1250    Volgograd switches to Moscow time on 2020-12-27 at 02:00.
1251
1252  Changes to future timestamps
1253
1254    Volgograd changes time zone from +04 to +03 on 2020-12-27 at 02:00.
1255    (Thanks to Alexander Krivenyshev and Stepan Golosunov.)
1256
1257  Changes to past timestamps
1258
1259    Correct many pre-1986 transitions, fixing entries originally
1260    derived from Shanks.  The fixes include:
1261      - Australia: several 1917 through 1971 transitions
1262      - The Bahamas: several 1941 through 1945 transitions
1263      - Bermuda: several 1917 through 1956 transitions
1264      - Belize: several 1942 through 1968 transitions
1265      - Ghana: several 1915 through 1956 transitions
1266      - Israel and Palestine: several 1940 through 1985 transitions
1267      - Kenya and adjacent: several 1908 through 1960 transitions
1268      - Nigeria and adjacent: correcting LMT in Lagos, and several 1905
1269        through 1919 transitions
1270      - Seychelles: the introduction of standard time in 1907, not 1906
1271      - Vanuatu: DST in 1973-1974, and a corrected 1984 transition
1272    (Thanks to P Chan.)
1273
1274    Because of the Australia change, Australia/Currie (King Island) is
1275    no longer needed, as it is identical to Australia/Hobart for all
1276    timestamps since 1970 and was therefore created by mistake.
1277    Australia/Currie has been moved to the 'backward' file and its
1278    corrected data moved to the 'backzone' file.
1279
1280  Changes to past time zone abbreviations and DST flags
1281
1282    To better match legislation in Turks and Caicos, the 2015 shift to
1283    year-round observance of -04 is now modeled as AST throughout before
1284    returning to Eastern Time with US DST in 2018, rather than as
1285    maintaining EDT until 2015-11-01.  (Thanks to P Chan.)
1286
1287  Changes to documentation
1288
1289    The zic man page now documents zic's coalescing of transitions
1290    when a zone falls back just before DST springs forward.
1291
1292
1293Release 2020d - 2020-10-21 11:24:13 -0700
1294
1295  Briefly:
1296    Palestine ends DST earlier than predicted, on 2020-10-24.
1297
1298  Changes to past and future timestamps
1299
1300    Palestine ends DST on 2020-10-24 at 01:00, instead of 2020-10-31
1301    as previously predicted (thanks to Sharef Mustafa.)  Its
1302    2019-10-26 fall-back was at 00:00, not 01:00 (thanks to Steffen
1303    Thorsen.)  Its 2015-10-23 transition was at 01:00 not 00:00, and
1304    its spring 2020 transition was on March 28 at 00:00, not March 27
1305    (thanks to Pierre Cashon.)  This affects Asia/Gaza and
1306    Asia/Hebron.  Assume future spring and fall transitions will be on
1307    the Saturday preceding the last Sunday of March and October,
1308    respectively.
1309
1310
1311Release 2020c - 2020-10-16 11:15:53 -0700
1312
1313  Briefly:
1314    Fiji starts DST later than usual, on 2020-12-20.
1315
1316  Changes to future timestamps
1317
1318    Fiji will start DST on 2020-12-20, instead of 2020-11-08 as
1319    previously predicted.  DST will still end on 2021-01-17.
1320    (Thanks to Raymond Kumar and Alan Mintz.)  Assume for now that
1321    the later-than-usual start date is a one-time departure from the
1322    recent pattern.
1323
1324  Changes to build procedure
1325
1326    Rearguard tarballs now contain an empty file pacificnew.
1327    Some older downstream software expects this file to exist.
1328    (Problem reported by Mike Cullinan.)
1329
1330
1331Release 2020b - 2020-10-06 18:35:04 -0700
1332
1333  Briefly:
1334    Revised predictions for Morocco's changes starting in 2023.
1335    Canada's Yukon changes to -07 on 2020-11-01, not 2020-03-08.
1336    Macquarie Island has stayed in sync with Tasmania since 2011.
1337    Casey, Antarctica is at +08 in winter and +11 in summer.
1338    zic no longer supports -y, nor the TYPE field of Rules.
1339
1340  Changes to future timestamps
1341
1342    Morocco's spring-forward after Ramadan is now predicted to occur
1343    no sooner than two days after Ramadan, instead of one day.
1344    (Thanks to Milamber.)  The first altered prediction is for 2023,
1345    now predicted to spring-forward on April 30 instead of April 23.
1346
1347  Changes to past and future timestamps
1348
1349   Casey Station, Antarctica has been using +08 in winter and +11 in
1350   summer since 2018.  The most recent transition from +08 to +11 was
1351   2020-10-04 00:01.  Also, Macquarie Island has been staying in
1352   sync with Tasmania since 2011.  (Thanks to Steffen Thorsen.)
1353
1354  Changes to past and future time zone abbreviations and DST flags
1355
1356    Canada's Yukon, represented by America/Whitehorse and
1357    America/Dawson, changes its time zone rules from -08/-07 to
1358    permanent -07 on 2020-11-01, not on 2020-03-08 as 2020a had it.
1359    This change affects only the time zone abbreviation (MST vs PDT)
1360    and daylight saving flag for the period between the two dates.
1361    (Thanks to Andrew G. Smith.)
1362
1363  Changes to past timestamps
1364
1365    Correct several transitions for Hungary for 1918/1983.
1366    For example, the 1983-09-25 fall-back was at 01:00, not 03:00.
1367    (Thanks to Géza Nyáry.)  Also, the 1890 transition to standard
1368    time was on 11-01, not 10-01 (thanks to Michael Deckers).
1369
1370    The 1891 French transition was on March 16, not March 15.  The
1371    1911-03-11 French transition was at midnight, not a minute later.
1372    Monaco's transitions were on 1892-06-01 and 1911-03-29, not
1373    1891-03-15 and 1911-03-11.  (Thanks to Michael Deckers.)
1374
1375  Changes to code
1376
1377    Support for zic's long-obsolete '-y YEARISTYPE' option has been
1378    removed and, with it, so has support for the TYPE field in Rule
1379    lines, which is now reserved for compatibility with earlier zic.
1380    These features were previously deprecated in release 2015f.
1381    (Thanks to Tim Parenti.)
1382
1383    zic now defaults to '-b slim' instead of to '-b fat'.
1384
1385    zic's new '-l -' and '-p -' options uninstall any existing
1386    localtime and posixrules files, respectively.
1387
1388    The undocumented and ineffective tzsetwall function has been
1389    removed.
1390
1391  Changes to build procedure
1392
1393    The Makefile now defaults POSIXRULES to '-', so the posixrules
1394    feature (obsolete as of 2019b) is no longer installed by default.
1395
1396  Changes to documentation and commentary
1397
1398    The long-obsolete files pacificnew, systemv, and yearistype.sh have
1399    been removed from the distribution.  (Thanks to Tim Parenti.)
1400
1401
1402Release 2020a - 2020-04-23 16:03:47 -0700
1403
1404  Briefly:
1405    Morocco springs forward on 2020-05-31, not 2020-05-24.
1406    Canada's Yukon advanced to -07 year-round on 2020-03-08.
1407    America/Nuuk renamed from America/Godthab.
1408    zic now supports expiration dates for leap second lists.
1409
1410  Changes to future timestamps
1411
1412    Morocco's second spring-forward transition in 2020 will be May 31,
1413    not May 24 as predicted earlier.  (Thanks to Semlali Naoufal.)
1414    Adjust future-year predictions to use the first Sunday after the
1415    day after Ramadan, not the first Sunday after Ramadan.
1416
1417    Canada's Yukon, represented by America/Whitehorse and
1418    America/Dawson, advanced to -07 year-round, beginning with its
1419    spring-forward transition on 2020-03-08, and will not fall back on
1420    2020-11-01.  Although a government press release calls this
1421    "permanent Pacific Daylight Saving Time", we prefer MST for
1422    consistency with nearby Dawson Creek, Creston, and Fort Nelson.
1423    (Thanks to Tim Parenti.)
1424
1425  Changes to past timestamps
1426
1427    Shanghai observed DST in 1919.  (Thanks to Phake Nick.)
1428
1429  Changes to timezone identifiers
1430
1431    To reflect current usage in English better, America/Godthab has
1432    been renamed to America/Nuuk.  A backwards-compatibility link
1433    remains for the old name.
1434
1435  Changes to code
1436
1437    localtime.c no longer mishandles timestamps after the last
1438    transition in a TZif file with leap seconds and with daylight
1439    saving time transitions projected into the indefinite future.
1440    For example, with TZ='America/Los_Angeles' with leap seconds,
1441    zdump formerly reported a DST transition on 2038-03-14
1442    from 01:59:32.999... to 02:59:33 instead of the correct transition
1443    from 01:59:59.999... to 03:00:00.
1444
1445    zic -L now supports an Expires line in the leapseconds file, and
1446    truncates the TZif output accordingly.  This propagates leap
1447    second expiration information into the TZif file, and avoids the
1448    abovementioned localtime.c bug as well as similar bugs present in
1449    many client implementations.  If no Expires line is present, zic
1450    -L instead truncates the TZif output based on the #expires comment
1451    present in leapseconds files distributed by tzdb 2018f and later;
1452    however, this usage is obsolescent.  For now, the distributed
1453    leapseconds file has an Expires line that is commented out, so
1454    that the file can be fed to older versions of zic which ignore the
1455    commented-out line.  Future tzdb distributions are planned to
1456    contain a leapseconds file with an Expires line.
1457
1458    The configuration macros HAVE_TZNAME and USG_COMPAT should now be
1459    set to 1 if the system library supports the feature, and 2 if not.
1460    As before, these macros are nonzero if tzcode should support the
1461    feature, zero otherwise.
1462
1463    The configuration macro ALTZONE now has the same values with the
1464    same meaning as HAVE_TZNAME and USG_COMPAT.
1465
1466    The code's defense against CRLF in leap-seconds.list is now
1467    portable to POSIX awk.  (Problem reported by Deborah Goldsmith.)
1468
1469    Although the undocumented tzsetwall function is not changed in
1470    this release, it is now deprecated in preparation for removal in
1471    future releases.  Due to POSIX requirements, tzsetwall has not
1472    worked for some time.  Any code that uses it should instead use
1473    tzalloc(NULL) or, if portability trumps thread-safety, should
1474    unset the TZ environment variable.
1475
1476  Changes to commentary
1477
1478    The Îles-de-la-Madeleine and the Listuguj reserve are noted as
1479    following America/Halifax, and comments about Yukon's "south" and
1480    "north" have been corrected to say "east" and "west".  (Thanks to
1481    Jeffery Nichols.)
1482
1483
1484Release 2019c - 2019-09-11 08:59:48 -0700
1485
1486  Briefly:
1487    Fiji observes DST from 2019-11-10 to 2020-01-12.
1488    Norfolk Island starts observing Australian-style DST.
1489
1490  Changes to future timestamps
1491
1492    Fiji's next DST transitions will be 2019-11-10 and 2020-01-12
1493    instead of 2019-11-03 and 2020-01-19.  (Thanks to Raymond Kumar.)
1494    Adjust future guesses accordingly.
1495
1496    Norfolk Island will observe Australian-style DST starting in
1497    spring 2019.  The first transition is on 2019-10-06.  (Thanks to
1498    Kyle Czech and Michael Deckers.)
1499
1500  Changes to past timestamps
1501
1502    Many corrections to time in Turkey from 1940 through 1985.
1503    (Thanks to Oya Vulaş via Alois Treindl, and to Kıvanç Yazan.)
1504
1505    The Norfolk Island 1975-03-02 transition was at 02:00 standard
1506    time, not 02:00 DST.  (Thanks to Michael Deckers.)
1507
1508    South Korea observed DST from 1948 through 1951.  Although this
1509    info was supposed to appear in release 2014j, a typo inadvertently
1510    suppressed the change.  (Thanks to Alois Treindl.)
1511
1512    Detroit observed DST in 1967 and 1968 following the US DST rules,
1513    except that its 1967 DST began on June 14 at 00:01.  (Thanks to
1514    Alois Treindl for pointing out that the old data entries were
1515    probably wrong.)
1516
1517    Fix several errors in pre-1970 transitions in Perry County, IN.
1518    (Thanks to Alois Treindl for pointing out the 1967/9 errors.)
1519
1520    Edmonton did not observe DST in 1967 or 1969.  In 1946 Vancouver
1521    ended DST on 09-29 not 10-13, and Vienna ended DST on 10-07 not
1522    10-06.  In 1945 Königsberg (now Kaliningrad) switched from +01/+02
1523    to +02/+03 on 04-10 not 01-01, and its +02/+03 is abbreviated
1524    EET/EEST, not CET/CEST.  (Thanks to Alois Treindl.)  In 1946
1525    Königsberg switched to +03 on 04-07 not 01-01.
1526
1527    In 1946 Louisville switched from CST to CDT on 04-28 at 00:01, not
1528    01-01 at 00:00.  (Thanks to Alois Treindl and Michael Deckers.)
1529    Also, it switched from CST to CDT on 1950-04-30, not 1947-04-27.
1530
1531    The 1892-05-01 transition in Brussels was at 00:17:30, not at noon.
1532    (Thanks to Michael Deckers.)
1533
1534  Changes to past time zone abbreviations and DST flags
1535
1536    Hong Kong Winter Time, observed from 1941-10-01 to 1941-12-25,
1537    is now flagged as DST and is abbreviated HKWT not HKT.
1538
1539  Changes to code
1540
1541    leapseconds.awk now relies only on its input data, rather than
1542    also relying on its comments.  (Inspired by code from Dennis
1543    Ferguson and Chris Woodbury.)
1544
1545    The code now defends against CRLFs in leap-seconds.list.
1546    (Thanks to Brian Inglis and Chris Woodbury.)
1547
1548  Changes to documentation and commentary
1549
1550    theory.html discusses leap seconds.  (Thanks to Steve Summit.)
1551
1552    Nashville's newspapers dueled about the time of day in the 1950s.
1553    (Thanks to John Seigenthaler.)
1554
1555    Liechtenstein observed Swiss DST in 1941/2.
1556    (Thanks to Alois Treindl.)
1557
1558
1559Release 2019b - 2019-07-01 00:09:53 -0700
1560
1561  Briefly:
1562    Brazil no longer observes DST.
1563    'zic -b slim' outputs smaller TZif files; please try it out.
1564    Palestine's 2019 spring-forward transition was on 03-29, not 03-30.
1565
1566  Changes to future timestamps
1567
1568    Brazil has canceled DST and will stay on standard time indefinitely.
1569    (Thanks to Steffen Thorsen, Marcus Diniz, and Daniel Soares de
1570    Oliveira.)
1571
1572    Predictions for Morocco now go through 2087 instead of 2037, to
1573    work around a problem on newlib when using TZif files output by
1574    zic 2019a or earlier.  (Problem reported by David Gauchard.)
1575
1576  Changes to past and future timestamps
1577
1578    Palestine's 2019 spring transition was 03-29 at 00:00, not 03-30
1579    at 01:00.  (Thanks to Sharef Mustafa and Even Scharning.)  Guess
1580    future transitions to be March's last Friday at 00:00.
1581
1582  Changes to past timestamps
1583
1584    Hong Kong's 1941-06-15 spring-forward transition was at 03:00, not
1585    03:30.  Its 1945 transition from JST to HKT was on 11-18 at 02:00,
1586    not 09-15 at 00:00.  In 1946 its spring-forward transition was on
1587    04-21 at 00:00, not the previous day at 03:30.  From 1946 through
1588    1952 its fall-back transitions occurred at 04:30, not at 03:30.
1589    In 1947 its fall-back transition was on 11-30, not 12-30.
1590    (Thanks to P Chan.)
1591
1592  Changes to past time zone abbreviations
1593
1594    Italy's 1866 transition to Rome Mean Time was on December 12, not
1595    September 22.  This affects only the time zone abbreviation for
1596    Europe/Rome between those dates.  (Thanks to Stephen Trainor and
1597    Luigi Rosa.)
1598
1599  Changes affecting metadata only
1600
1601    Add info about the Crimea situation in zone1970.tab and zone.tab.
1602    (Problem reported by Serhii Demediuk.)
1603
1604  Changes to code
1605
1606    zic's new -b option supports a way to control data bloat and to
1607    test for year-2038 bugs in software that reads TZif files.
1608    'zic -b fat' and 'zic -b slim' generate larger and smaller output;
1609    for example, changing from fat to slim shrinks the Europe/London
1610    file from 3648 to 1599 bytes, saving about 56%.  Fat and slim
1611    files represent the same set of timestamps and use the same TZif
1612    format as documented in tzfile(5) and in Internet RFC 8536.
1613    Fat format attempts to work around bugs or incompatibilities in
1614    older software, notably software that mishandles 64-bit TZif data
1615    or uses obsolete TZ strings like "EET-2EEST" that lack DST rules.
1616    Slim format is more efficient and does not work around 64-bit bugs
1617    or obsolete TZ strings.  Currently zic defaults to fat format
1618    unless you compile with -DZIC_BLOAT_DEFAULT=\"slim\"; this
1619    out-of-the-box default is intended to change in future releases
1620    as the buggy software often mishandles timestamps anyway.
1621
1622    zic no longer treats a set of rules ending in 2037 specially.
1623    Previously, zic assumed that such a ruleset meant that future
1624    timestamps could not be predicted, and therefore omitted a
1625    POSIX-like TZ string in the TZif output.  The old behavior is no
1626    longer needed for current tzdata, and caused problems with newlib
1627    when used with older tzdata (reported by David Gauchard).
1628
1629    zic no longer generates some artifact transitions.  For example,
1630    Europe/London no longer has a no-op transition in January 1996.
1631
1632  Changes to build procedure
1633
1634    tzdata.zi now assumes zic 2017c or later.  This shrinks tzdata.zi
1635    by a percent or so.
1636
1637  Changes to documentation and commentary
1638
1639    The Makefile now documents the POSIXRULES macro as being obsolete,
1640    and similarly, zic's -p POSIXRULES option is now documented as
1641    being obsolete.  Although the POSIXRULES feature still exists and
1642    works as before, in practice it is rarely used for its intended
1643    purpose, and it does not work either in the default reference
1644    implementation (for timestamps after 2037) or in common
1645    implementations such as GNU/Linux (for contemporary timestamps).
1646    Since POSIXRULES was designed primarily as a temporary transition
1647    facility for System V platforms that died off decades ago, it is
1648    being decommissioned rather than institutionalized.
1649
1650    New info on Bonin Islands and Marcus (thanks to Wakaba and Phake Nick).
1651
1652
1653Release 2019a - 2019-03-25 22:01:33 -0700
1654
1655  Briefly:
1656    Palestine "springs forward" on 2019-03-30 instead of 2019-03-23.
1657    Metlakatla "fell back" to rejoin Alaska Time on 2019-01-20 at 02:00.
1658
1659  Changes to past and future timestamps
1660
1661    Palestine will not start DST until 2019-03-30, instead of 2019-03-23 as
1662    previously predicted.  Adjust our prediction by guessing that spring
1663    transitions will be between 24 and 30 March, which matches recent practice
1664    since 2016.  (Thanks to Even Scharning and Tim Parenti.)
1665
1666    Metlakatla ended its observance of Pacific standard time,
1667    rejoining Alaska Time, on 2019-01-20 at 02:00.  (Thanks to Ryan
1668    Stanley and Tim Parenti.)
1669
1670  Changes to past timestamps
1671
1672    Israel observed DST in 1980 (08-02/09-13) and 1984 (05-05/08-25).
1673    (Thanks to Alois Treindl and Isaac Starkman.)
1674
1675  Changes to time zone abbreviations
1676
1677    Etc/UCT is now a backward-compatibility link to Etc/UTC, instead
1678    of being a separate zone that generates the abbreviation "UCT",
1679    which nowadays is typically a typo.  (Problem reported by Isiah
1680    Meadows.)
1681
1682  Changes to code
1683
1684    zic now has an -r option to limit the time range of output data.
1685    For example, 'zic -r @1000000000' limits the output data to
1686    timestamps starting 1000000000 seconds after the Epoch.
1687    This helps shrink output size and can be useful for applications
1688    not needing the full timestamp history, such as TZDIST truncation;
1689    see Internet RFC 8536 section 5.1.  (Inspired by a feature request
1690    from Christopher Wong, helped along by bug reports from Wong and
1691    from Tim Parenti.)
1692
1693  Changes to documentation
1694
1695    Mention Internet RFC 8536 (February 2019), which documents TZif.
1696
1697    tz-link.html now cites tzdata-meta
1698    <https://tzdata-meta.timtimeonline.com/>.
1699
1700
1701Release 2018i - 2018-12-30 11:05:43 -0800
1702
1703  Briefly:
1704    São Tomé and Príncipe switches from +01 to +00 on 2019-01-01.
1705
1706  Changes to future timestamps
1707
1708    Due to a change in government, São Tomé and Príncipe switches back
1709    from +01 to +00 on 2019-01-01 at 02:00.  (Thanks to Vadim
1710    Nasardinov and Michael Deckers.)
1711
1712
1713Release 2018h - 2018-12-23 17:59:32 -0800
1714
1715  Briefly:
1716    Qyzylorda, Kazakhstan moved from +06 to +05 on 2018-12-21.
1717    New zone Asia/Qostanay because Qostanay, Kazakhstan didn't move.
1718    Metlakatla, Alaska observes PST this winter only.
1719    Guess Morocco will continue to adjust clocks around Ramadan.
1720    Add predictions for Iran from 2038 through 2090.
1721
1722  Changes to future timestamps
1723
1724    Guess that Morocco will continue to fall back just before and
1725    spring forward just after Ramadan, the practice since 2012.
1726    (Thanks to Maamar Abdelkader.)  This means Morocco will observe
1727    negative DST during Ramadan in main and vanguard formats, and in
1728    rearguard format it stays in the +00 timezone and observes
1729    ordinary DST in all months other than Ramadan.  As before, extend
1730    this guesswork to the year 2037.  As a consequence, Morocco is
1731    scheduled to observe three DST transitions in some Gregorian years
1732    (e.g., 2033) due to the mismatch between the Gregorian and Islamic
1733    calendars.
1734
1735    The table of exact transitions for Iranian DST has been extended.
1736    It formerly cut off before the year 2038 in a nod to 32-bit time_t.
1737    It now cuts off before 2091 as there is doubt about how the Persian
1738    calendar will treat 2091.  This change predicts DST transitions in
1739    2038-9, 2042-3, and 2046-7 to occur one day later than previously
1740    predicted.  As before, post-cutoff transitions are approximated.
1741
1742  Changes to past and future timestamps
1743
1744    Qyzylorda (aka Kyzylorda) oblast in Kazakhstan moved from +06 to
1745    +05 on 2018-12-21.  This is a zone split as Qostanay (aka
1746    Kostanay) did not switch, so create a zone Asia/Qostanay.
1747
1748    Metlakatla moved from Alaska to Pacific standard time on 2018-11-04.
1749    It did not change clocks that day and remains on -08 this winter.
1750    (Thanks to Ryan Stanley.)  It will revert to the usual Alaska
1751    rules next spring, so this change affects only timestamps
1752    from 2018-11-04 through 2019-03-10.
1753
1754  Change to past timestamps
1755
1756    Kwajalein's 1993-08-20 transition from -12 to +12 was at 24:00,
1757    not 00:00.  I transcribed the time incorrectly from Shanks.
1758    (Thanks to Phake Nick.)
1759
1760    Nauru's 1979 transition was on 02-10 at 02:00, not 05-01 at 00:00.
1761    (Thanks to Phake Nick.)
1762
1763    Guam observed DST irregularly from 1959 through 1977.
1764    (Thanks to Phake Nick.)
1765
1766    Hong Kong observed DST in 1941 starting 06-15 (not 04-01), then on
1767    10-01 changed standard time to +08:30 (not +08).  Its transition
1768    back to +08 after WWII was on 1945-09-15, not the previous day.
1769    Its 1904-10-30 change took effect at 01:00 +08 (not 00:00 LMT).
1770    (Thanks to Phake Nick, Steve Allen, and Joseph Myers.)  Also,
1771    its 1952 fallback was on 11-02 (not 10-25).
1772
1773    This release contains many changes to timestamps before 1946 due
1774    to Japanese possession or occupation of Pacific/Chuuk,
1775    Pacific/Guam, Pacific/Kosrae, Pacific/Kwajalein, Pacific/Majuro,
1776    Pacific/Nauru, Pacific/Palau, and Pacific/Pohnpei.
1777    (Thanks to Phake Nick.)
1778
1779    Assume that the Spanish East Indies was like the Philippines and
1780    observed American time until the end of 1844.  This affects
1781    Pacific/Chuuk, Pacific/Kosrae, Pacific/Palau, and Pacific/Pohnpei.
1782
1783  Changes to past tm_isdst flags
1784
1785    For the recent Morocco change, the tm_isdst flag should be 1 from
1786    2018-10-27 00:00 to 2018-10-28 03:00.  (Thanks to Michael Deckers.)
1787    Give a URL to the official decree.  (Thanks to Matt Johnson.)
1788
1789
1790Release 2018g - 2018-10-26 22:22:45 -0700
1791
1792  Briefly:
1793    Morocco switches to permanent +01 on 2018-10-28.
1794
1795  Changes to future timestamps
1796
1797    Morocco switches from +00/+01 to permanent +01 effective 2018-10-28,
1798    so its clocks will not fall back as previously scheduled.
1799    (Thanks to Mohamed Essedik Najd and Brian Inglis.)
1800
1801  Changes to code
1802
1803    When generating TZif files with leap seconds, zic no longer uses a
1804    format that trips up older 32-bit clients, fixing a bug introduced
1805    in 2018f.  (Reported by Daniel Fischer.)  Also, the zic workaround
1806    for QTBUG-53071 now also works for TZif files with leap seconds.
1807
1808    The translator to rearguard format now rewrites the line
1809    "Rule Japan 1948 1951 - Sep Sat>=8 25:00 0 S" to
1810    "Rule Japan 1948 1951 - Sep Sun>=9  1:00 0 S".
1811    This caters to zic before 2007 and to Oracle TZUpdater 2.2.0
1812    and earlier.  (Reported by Christos Zoulas.)
1813
1814  Changes to past time zone abbreviations
1815
1816    Change HDT to HWT/HPT for WWII-era abbreviations in Hawaii.
1817    This reverts to 2011h, as the abbreviation change in 2011i was
1818    likely inadvertent.
1819
1820  Changes to documentation
1821
1822    tzfile.5 has new sections on interoperability issues.
1823
1824
1825Release 2018f - 2018-10-18 00:14:18 -0700
1826
1827  Briefly:
1828  Volgograd moves from +03 to +04 on 2018-10-28.
1829  Fiji ends DST 2019-01-13, not 2019-01-20.
1830  Most of Chile changes DST dates, effective 2019-04-06.
1831
1832  Changes to future timestamps
1833
1834    Volgograd moves from +03 to +04 on 2018-10-28 at 02:00.
1835    (Thanks to Alexander Fetisov and Stepan Golosunov.)
1836
1837    Fiji ends DST 2019-01-13 instead of the 2019-01-20 previously
1838    predicted.  (Thanks to Raymond Kumar.)  Adjust future predictions
1839    accordingly.
1840
1841    Most of Chile will end DST on the first Saturday in April at 24:00 mainland
1842    time, and resume DST on the first Saturday in September at 24:00 mainland
1843    time.  The changes are effective from 2019-04-06, and do not affect the
1844    Magallanes region modeled by America/Punta_Arenas.  (Thanks to Juan Correa
1845    and Tim Parenti.)  Adjust future predictions accordingly.
1846
1847  Changes to past timestamps
1848
1849    The 2018-05-05 North Korea 30-minute time zone change took place
1850    at 23:30 the previous day, not at 00:00 that day.
1851
1852    China's 1988 spring-forward transition was on April 17, not
1853    April 10.  Its DST transitions in 1986/91 were at 02:00, not 00:00.
1854    (Thanks to P Chan.)
1855
1856    Fix several issues for Macau before 1992.  Macau's pre-1904 LMT
1857    was off by 10 s.  Macau switched to +08 in 1904 not 1912, and
1858    temporarily switched to +09/+10 during World War II.  Macau
1859    observed DST in 1942/79, not 1961/80, and there were several
1860    errors for transition times and dates.  (Thanks to P Chan.)
1861
1862    The 1948-1951 fallback transitions in Japan were at 25:00 on
1863    September's second Saturday, not at 24:00.  (Thanks to Phake Nick.)
1864    zic turns this into 01:00 on the day after September's second
1865    Saturday, which is the best that POSIX or C platforms can do.
1866
1867    Incorporate 1940-1949 Asia/Shanghai DST transitions from a 2014
1868    paper by Li Yu, replacing more-questionable data from Shanks.
1869
1870  Changes to time zone abbreviations
1871
1872    Use "PST" and "PDT" for Philippine time.  (Thanks to Paul Goyette.)
1873
1874  Changes to code
1875
1876    zic now always generates TZif files where time type 0 is used for
1877    timestamps before the first transition.  This simplifies the
1878    reading of TZif files and should not affect behavior of existing
1879    TZif readers because the same set of time types is used; only
1880    their internal indexes may have changed.  This affects only the
1881    legacy zones EST5EDT, CST6CDT, MST7MDT, PST8PDT, CET, MET, and
1882    EET, which previously used nonzero types for these timestamps.
1883
1884    Because of the type 0 change, zic no longer outputs a dummy
1885    transition at time -2**59 (before the Big Bang), as clients should
1886    no longer need this to handle historical timestamps correctly.
1887    This reverts a change introduced in 2013d and shrinks most TZif
1888    files by a few bytes.
1889
1890    zic now supports negative time-of-day in Rule and Leap lines, e.g.,
1891    "Rule X min max - Apr lastSun -6:00 1:00 -" means the transition
1892    occurs at 18:00 on the Saturday before the last Sunday in April.
1893    This behavior was documented in 2018a but the code did not
1894    entirely match the documentation.
1895
1896    localtime.c no longer requires at least one time type in TZif
1897    files that lack transitions or have a POSIX-style TZ string.  This
1898    future-proofs the code against possible future extensions to the
1899    format that would allow TZif files with POSIX-style TZ strings and
1900    without transitions or time types.
1901
1902    A read-access subscript error in localtime.c has been fixed.
1903    It could occur only in TZif files with timecnt == 0, something that
1904    does not happen in practice now but could happen in future versions.
1905
1906    localtime.c no longer ignores TZif POSIX-style TZ strings that
1907    specify only standard time.  Instead, these TZ strings now
1908    override the default time type for timestamps after the last
1909    transition (or for all timestamps if there are no transitions),
1910    just as DST strings specifying DST have always done.
1911
1912    leapseconds.awk now outputs "#updated" and "#expires" comments,
1913    and supports leap seconds at the ends of months other than June
1914    and December.  (Inspired by suggestions from Chris Woodbury.)
1915
1916  Changes to documentation
1917
1918    New restrictions: A Rule name must start with a character that
1919    is neither an ASCII digit nor "-" nor "+", and an unquoted name
1920    should not use characters in the set "!$%&'()*,/:;<=>?@[\]^`{|}~".
1921    The latter restriction makes room for future extensions (a
1922    possibility noted by Tom Lane).
1923
1924    tzfile.5 now documents what time types apply before the first and
1925    after the last transition, if any.
1926
1927    Documentation now uses the spelling "timezone" for a TZ setting
1928    that determines timestamp history, and "time zone" for a
1929    geographic region currently sharing the same standard time.
1930
1931    The name "TZif" is now used for the tz binary data format.
1932
1933    tz-link.htm now mentions the A0 TimeZone Migration utilities.
1934    (Thanks to Aldrin Martoq for the link.)
1935
1936  Changes to build procedure
1937
1938    New 'make' target 'rearguard_tarballs' to build the rearguard
1939    tarball only.  This is a convenience on platforms that lack lzip
1940    if you want to build the rearguard tarball.  (Problem reported by
1941    Deborah Goldsmith.)
1942
1943    tzdata.zi is now more stable from release to release.  (Problem
1944    noted by Tom Lane.)  It is also a bit shorter.
1945
1946    tzdata.zi now can contain comment lines documenting configuration
1947    information, such as which data format was selected, which input
1948    files were used, and how leap seconds are treated.  (Problems
1949    noted by Lester Caine and Brian Inglis.)  If the Makefile defaults
1950    are used these comment lines are absent, for backward
1951    compatibility.  A redistributor intending to alter its copy of the
1952    files should also append "-LABEL" to the 'version' file's first
1953    line, where "LABEL" identifies the redistributor's change.
1954
1955
1956Release 2018e - 2018-05-01 23:42:51 -0700
1957
1958  Briefly:
1959
1960    North Korea switches back to +09 on 2018-05-05.
1961    The main format uses negative DST again, for Ireland etc.
1962    'make tarballs' now also builds a rearguard tarball.
1963    New 's' and 'd' suffixes in SAVE columns of Rule and Zone lines.
1964
1965  Changes to past and future timestamps
1966
1967    North Korea switches back from +0830 to +09 on 2018-05-05.
1968    (Thanks to Kang Seonghoon, Arthur David Olson, Seo Sanghyeon,
1969    and Tim Parenti.)
1970
1971    Bring back the negative-DST changes of 2018a, except be more
1972    compatible with data parsers that do not support negative DST.
1973    Also, this now affects historical timestamps in Namibia and the
1974    former Czechoslovakia, not just Ireland.  The main format now uses
1975    negative DST to model timestamps in Europe/Dublin (from 1971 on),
1976    Europe/Prague (1946/7), and Africa/Windhoek (1994/2017).  This
1977    does not affect UT offsets, only time zone abbreviations and the
1978    tm_isdst flag.  Also, this does not affect rearguard or vanguard
1979    formats; effectively the main format now uses vanguard instead of
1980    rearguard format.  Data parsers that do not support negative DST
1981    can still use data from the rearguard tarball described below.
1982
1983  Changes to build procedure
1984
1985    The command 'make tarballs' now also builds the tarball
1986    tzdataVERSION-rearguard.tar.gz, which is like tzdataVERSION.tar.gz
1987    except that it uses rearguard format intended for trailing-edge
1988    data parsers.
1989
1990  Changes to data format and to code
1991
1992    The SAVE column of Rule and Zone lines can now have an 's' or 'd'
1993    suffix, which specifies whether the adjusted time is standard time
1994    or daylight saving time.  If no suffix is given, daylight saving
1995    time is used if and only if the SAVE column is nonzero; this is
1996    the longstanding behavior.  Although this new feature is not used
1997    in tzdata, it could be used to specify the legal time in Namibia
1998    1994-2017, as opposed to the popular time (see below).
1999
2000  Changes to past timestamps
2001
2002    From 1994 through 2017 Namibia observed DST in winter, not summer.
2003    That is, it used negative DST, as Ireland still does.  This change
2004    does not affect UTC offsets; it affects only the tm_isdst flag and
2005    the abbreviation used during summer, which is now CAT, not WAST.
2006    Although (as noted by Michael Deckers) summer and winter time were
2007    both simply called "standard time" in Namibian law, in common
2008    practice winter time was considered to be DST (as noted by Stephen
2009    Colebourne).  The full effect of this change is only in vanguard
2010    and main format; in rearguard format, the tm_isdst flag is still
2011    zero in winter and nonzero in summer.
2012
2013    In 1946/7 Czechoslovakia also observed negative DST in winter.
2014    The full effect of this change is only in vanguard and main
2015    formats; in rearguard format, it is modeled as plain GMT without
2016    daylight saving.  Also, the dates of some 1944/5 DST transitions
2017    in Czechoslovakia have been changed.
2018
2019
2020Release 2018d - 2018-03-22 07:05:46 -0700
2021
2022  Briefly:
2023
2024  Palestine starts DST a week earlier in 2018.
2025  Add support for vanguard and rearguard data consumers.
2026  Add subsecond precision to source data format, though not to data.
2027
2028  Changes to future timestamps
2029
2030    In 2018, Palestine starts DST on March 24, not March 31.
2031    Adjust future predictions accordingly.  (Thanks to Sharef Mustafa.)
2032
2033  Changes to past and future timestamps
2034
2035    Casey Station in Antarctica changed from +11 to +08 on 2018-03-11
2036    at 04:00.  (Thanks to Steffen Thorsen.)
2037
2038  Changes to past timestamps
2039
2040    Historical transitions for Uruguay, represented by
2041    America/Montevideo, have been updated per official legal documents,
2042    replacing previous data mainly originating from the inventions of
2043    Shanks & Pottenger.  This has resulted in adjustments ranging from
2044    30 to 90 minutes in either direction over at least two dozen
2045    distinct periods ranging from one day to several years in length.
2046    A mere handful of pre-1991 transitions are unaffected; data since
2047    then has come from more reliable contemporaneous reporting.  These
2048    changes affect various timestamps in 1920-1923, 1936, 1939,
2049    1942-1943, 1959, 1966-1970, 1972, 1974-1980, and 1988-1990.
2050    Additionally, Uruguay's pre-standard-time UT offset has been
2051    adjusted westward by 7 seconds, from UT-03:44:44 to UT-03:44:51, to
2052    match the location of the Observatory of the National Meteorological
2053    Institute in Montevideo.
2054    (Thanks to Jeremie Bonjour, Tim Parenti, and Michael Deckers.)
2055
2056    East Kiribati skipped New Year's Eve 1994, not New Year's Day 1995.
2057    (Thanks to Kerry Shetline.)
2058
2059    Fix the 1912-01-01 transition for Portugal and its colonies.
2060    This transition was at 00:00 according to the new UT offset, not
2061    according to the old one.  Also assume that Cape Verde switched on
2062    the same date as the rest, not in 1907.  This affects
2063    Africa/Bissau, Africa/Sao_Tome, Asia/Macau, Atlantic/Azores,
2064    Atlantic/Cape_Verde, Atlantic/Madeira, and Europe/Lisbon.
2065    (Thanks to Michael Deckers.)
2066
2067    Fix an off-by-1 error for pre-1913 timestamps in Jamaica and in
2068    Turks & Caicos.
2069
2070  Changes to past time zone abbreviations
2071
2072    MMT took effect in Uruguay from 1908-06-10, not 1898-06-28.  There
2073    is no clock change associated with the transition.
2074
2075  Changes to build procedure
2076
2077    The new DATAFORM macro in the Makefile lets the installer choose
2078    among three source data formats.  The idea is to lessen downstream
2079    disruption when data formats are improved.
2080
2081    * DATAFORM=vanguard installs from the latest, bleeding-edge
2082      format.  DATAFORM=main (the default) installs from the format
2083      used in the 'africa' etc. files.  DATAFORM=rearguard installs
2084      from a trailing-edge format.  Eventually, elements of today's
2085      vanguard format should move to the main format, and similarly
2086      the main format's features should eventually move to the
2087      rearguard format.
2088
2089    * In the current version, the main and rearguard formats are
2090      identical and match that of 2018c, so this change does not
2091      affect default behavior.  The vanguard format currently contains
2092      one feature not in the main format: negative SAVE values.  This
2093      improves support for Ireland, which uses Irish Standard Time
2094      (IST, UTC+01) in summer and GMT (UTC) in winter.  tzcode has
2095      supported negative SAVE values for decades, and this feature
2096      should move to the main format soon.  However, it will not move
2097      to the rearguard format for quite some time because some
2098      downstream parsers do not support it.
2099
2100    * The build procedure constructs three files vanguard.zi, main.zi,
2101      and rearguard.zi, one for each format.  Although the files
2102      represent essentially the same data, they may have minor
2103      discrepancies that users are not likely to notice.  The files
2104      are intended for downstream data consumers and are not
2105      installed.  Zoneinfo parsers that do not support negative SAVE values
2106      should start using rearguard.zi, so that they will be unaffected
2107      when the negative-DST feature moves from vanguard to main.
2108      Bleeding-edge Zoneinfo parsers that support the new features
2109      already can use vanguard.zi; in this respect, current tzcode is
2110      bleeding-edge.
2111
2112    The Makefile should now be safe for parallelized builds, and 'make
2113    -j to2050new.tzs' is now much faster on a multiprocessor host
2114    with GNU Make.
2115
2116    When built with -DSUPPRESS_TZDIR, the tzcode library no longer
2117    prepends TZDIR/ to file names that do not begin with '/'.  This is
2118    not recommended for general use, due to its security implications.
2119    (From a suggestion by Manuela Friedrich.)
2120
2121  Changes to code
2122
2123    zic now accepts subsecond precision in expressions like
2124    00:19:32.13, which is approximately the legal time of the
2125    Netherlands from 1835 to 1937.  However, because it is
2126    questionable whether the few recorded uses of non-integer offsets
2127    had subsecond precision in practice, there are no plans for tzdata
2128    to use this feature.  (Thanks to Steve Allen for pointing out
2129    the limitations of historical data in this area.)
2130
2131    The code is a bit more portable to MS-Windows.  Installers can
2132    compile with -DRESERVE_STD_EXT_IDS on MS-Windows platforms that
2133    reserve identifiers like 'localtime'.  (Thanks to Manuela
2134    Friedrich.)
2135
2136  Changes to documentation and commentary
2137
2138    theory.html now outlines tzdb's extensions to POSIX's model for
2139    civil time, and has a section "POSIX features no longer needed"
2140    that lists POSIX API components that are now vestigial.
2141    (From suggestions by Steve Summit.)  It also better distinguishes
2142    time zones from tz regions.  (From a suggestion by Guy Harris.)
2143
2144    Commentary is now more consistent about using the phrase "daylight
2145    saving time", to match the C name tm_isdst.  Daylight saving time
2146    need not occur in summer, and need not have a positive offset from
2147    standard time.
2148
2149    Commentary about historical transitions in Uruguay has been expanded
2150    with links to many relevant legal documents.
2151    (Thanks to Tim Parenti.)
2152
2153    Commentary now uses some non-ASCII characters with Unicode value
2154    less than U+0100, as they can be useful and should work even with
2155    older editors such as XEmacs.
2156
2157
2158Release 2018c - 2018-01-22 23:00:44 -0800
2159
2160  Briefly:
2161  Revert Irish changes that relied on negative SAVE values.
2162
2163  Changes to tm_isdst
2164
2165    Revert the 2018a change to Europe/Dublin.  As before, this change
2166    does not affect UT offsets or abbreviations; it affects only
2167    whether timestamps are considered to be standard time or
2168    daylight-saving time, as expressed in the tm_isdst flag of C's
2169    struct tm type.  This reversion is intended to be a temporary
2170    workaround for problems discovered with downstream uses of
2171    releases 2018a and 2018b, which implemented Irish time by using
2172    negative SAVE values in the Eire rules of the 'europe' file.
2173    Although negative SAVE values have been part of tzcode for many
2174    years and are supported by many platforms, they were not
2175    documented before 2018a and ICU and OpenJDK do not currently
2176    support them.  A mechanism to export data to platforms lacking
2177    support for negative DST is planned to be developed before the
2178    change is reapplied.  (Problems reported by Deborah Goldsmith and
2179    Stephen Colebourne.)
2180
2181  Changes to past timestamps
2182
2183    Japanese DST transitions (1948-1951) were Sundays at 00:00, not
2184    Saturdays or Sundays at 02:00.  (Thanks to Takayuki Nikai.)
2185
2186  Changes to build procedure
2187
2188    The build procedure now works around mawk 1.3.3's lack of support
2189    for character class expressions.  (Problem reported by Ohyama.)
2190
2191
2192Release 2018b - 2018-01-17 23:24:48 -0800
2193
2194  Briefly:
2195  Fix a packaging problem in tz2018a, which was missing 'pacificnew'.
2196
2197  Changes to build procedure
2198
2199    The distribution now contains the file 'pacificnew' again.
2200    This file was inadvertently omitted in the 2018a distribution.
2201    (Problem reported by Matias Fonzo.)
2202
2203
2204Release 2018a - 2018-01-12 22:29:21 -0800
2205
2206  Briefly:
2207  São Tomé and Príncipe switched from +00 to +01.
2208  Brazil's DST will now start on November's first Sunday.
2209  Ireland's standard time is now in the summer, not the winter.
2210  Use Debian-style installation locations, instead of 4.3BSD-style.
2211  New zic option -t.
2212
2213  Changes to past and future timestamps
2214
2215    São Tomé and Príncipe switched from +00 to +01 on 2018-01-01 at
2216    01:00.  (Thanks to Steffen Thorsen and Michael Deckers.)
2217
2218  Changes to future timestamps
2219
2220    Starting in 2018 southern Brazil will begin DST on November's
2221    first Sunday instead of October's third Sunday.  (Thanks to
2222    Steffen Thorsen.)
2223
2224  Changes to past timestamps
2225
2226    A discrepancy of 4 s in timestamps before 1931 in South Sudan has
2227    been corrected.  The 'backzone' and 'zone.tab' files did not agree
2228    with the 'africa' and 'zone1970.tab' files.  (Problem reported by
2229    Michael Deckers.)
2230
2231    The abbreviation invented for Bolivia Summer Time (1931-2) is now
2232    BST instead of BOST, to be more consistent with the convention
2233    used for Latvian Summer Time (1918-9) and for British Summer Time.
2234
2235  Changes to tm_isdst
2236
2237    Change Europe/Dublin so that it observes Irish Standard Time (UT
2238    +01) in summer and GMT (as negative daylight-saving) in winter,
2239    instead of observing standard time (GMT) in winter and Irish
2240    Summer Time (UT +01) in summer.  This change does not affect UT
2241    offsets or abbreviations; it affects only whether timestamps are
2242    considered to be standard time or daylight-saving time, as
2243    expressed in the tm_isdst flag of C's struct tm type.
2244    (Discrepancy noted by Derick Rethans.)
2245
2246  Changes to build procedure
2247
2248    The default installation locations have been changed to mostly
2249    match Debian circa 2017, instead of being designed as an add-on to
2250    4.3BSD circa 1986.  This affects the Makefile macros TOPDIR,
2251    TZDIR, MANDIR, and LIBDIR.  New Makefile macros TZDEFAULT, USRDIR,
2252    USRSHAREDIR, BINDIR, ZDUMPDIR, and ZICDIR let installers tailor
2253    locations more precisely.  (This responds to suggestions from
2254    Brian Inglis and from Steve Summit.)
2255
2256    The default installation procedure no longer creates the
2257    backward-compatibility link US/Pacific-New, which causes
2258    confusion during user setup (e.g., see Debian bug 815200).
2259    Use 'make BACKWARD="backward pacificnew"' to create the link
2260    anyway, for now.  Eventually we plan to remove the link entirely.
2261
2262    tzdata.zi now contains a version-number comment.
2263    (Suggested by Tom Lane.)
2264
2265    The Makefile now quotes values like BACKWARD more carefully when
2266    passing them to the shell.  (Problem reported by Zefram.)
2267
2268    Builders no longer need to specify -DHAVE_SNPRINTF on platforms
2269    that have snprintf and use pre-C99 compilers.  (Problem reported
2270    by Jon Skeet.)
2271
2272  Changes to code
2273
2274    zic has a new option -t FILE that specifies the location of the
2275    file that determines local time when TZ is unset.  The default for
2276    this location can be configured via the new TZDEFAULT makefile
2277    macro, which defaults to /etc/localtime.
2278
2279    Diagnostics and commentary now distinguish UT from UTC more
2280    carefully; see theory.html for more information about UT vs UTC.
2281
2282    zic has been ported to GCC 8's -Wstringop-truncation option.
2283    (Problem reported by Martin Sebor.)
2284
2285  Changes to documentation and commentary
2286
2287    The zic man page now documents the longstanding behavior that
2288    times and years can be out of the usual range, with negative times
2289    counting backwards from midnight and with year 0 preceding year 1.
2290    (Problem reported by Michael Deckers.)
2291
2292    The theory.html file now mentions the POSIX limit of six chars
2293    per abbreviation, and lists alphabetic abbreviations used.
2294
2295    The files tz-art.htm and tz-link.htm have been renamed to
2296    tz-art.html and tz-link.html, respectively, for consistency with
2297    other file names and to simplify web server configuration.
2298
2299
2300Release 2017c - 2017-10-20 14:49:34 -0700
2301
2302  Briefly:
2303  Northern Cyprus switches from +03 to +02/+03 on 2017-10-29.
2304  Fiji ends DST 2018-01-14, not 2018-01-21.
2305  Namibia switches from +01/+02 to +02 on 2018-04-01.
2306  Sudan switches from +03 to +02 on 2017-11-01.
2307  Tonga likely switches from +13/+14 to +13 on 2017-11-05.
2308  Turks & Caicos switches from -04 to -05/-04 on 2018-11-04.
2309  A new file tzdata.zi now holds a small text copy of all data.
2310  The zic input format has been regularized slightly.
2311
2312  Changes to future timestamps
2313
2314    Northern Cyprus has decided to resume EU rules starting
2315    2017-10-29, thus reinstituting winter time.
2316
2317    Fiji ends DST 2018-01-14 instead of the 2018-01-21 previously
2318    predicted.  (Thanks to Dominic Fok.)  Adjust future predictions
2319    accordingly.
2320
2321    Namibia will switch from +01 with DST to +02 all year on
2322    2017-09-03 at 02:00.  This affects UT offsets starting 2018-04-01
2323    at 02:00.  (Thanks to Steffen Thorsen.)
2324
2325    Sudan will switch from +03 to +02 on 2017-11-01.  (Thanks to Ahmed
2326    Atyya and Yahia Abdalla.)  South Sudan is not switching, so
2327    Africa/Juba is no longer a link to Africa/Khartoum.
2328
2329    Tonga has likely ended its experiment with DST, and will not
2330    adjust its clocks on 2017-11-05.  Although Tonga has not announced
2331    whether it will continue to observe DST, the IATA is assuming that
2332    it will not.  (Thanks to David Wade.)
2333
2334    Turks & Caicos will switch from -04 all year to -05 with US DST on
2335    2018-03-11 at 03:00.  This affects UT offsets starting 2018-11-04
2336    at 02:00.  (Thanks to Steffen Thorsen.)
2337
2338  Changes to past timestamps
2339
2340    Namibia switched from +02 to +01 on 1994-03-21, not 1994-04-03.
2341    (Thanks to Arthur David Olson.)
2342
2343    Detroit did not observe DST in 1967.
2344
2345    Use railway time for Asia/Kolkata before 1941, by switching to
2346    Madras local time (UT +052110) in 1870, then to IST (UT +0530) in
2347    1906.  Also, treat 1941-2's +0630 as DST, like 1942-5.
2348
2349    Europe/Dublin's 1946 and 1947 fallback transitions occurred at
2350    02:00 standard time, not 02:00 DST.  (Thanks to Michael Deckers.)
2351
2352    Pacific/Apia and Pacific/Pago_Pago switched from Antipodean to
2353    American time in 1892, not 1879.  (Thanks to Michael Deckers.)
2354
2355    Adjust the 1867 transition in Alaska to better reflect the
2356    historical record, by changing it to occur on 1867-10-18 at 15:30
2357    Sitka time rather than at the start of 1867-10-17 local time.
2358    Although strictly speaking this is accurate only for Sitka,
2359    the rest of Alaska's blanks need to be filled in somehow.
2360
2361    Fix off-by-one errors in UT offsets for Adak and Nome before 1867.
2362    (Thanks to Michael Deckers.)
2363
2364    Add 7 s to the UT offset in Asia/Yangon before 1920.
2365
2366  Changes to zone names
2367
2368    Remove Canada/East-Saskatchewan from the 'backward' file, as it
2369    exceeded the 14-character limit and was an unused misnomer anyway.
2370
2371  Changes to build procedure
2372
2373    To support applications that prefer to read time zone data in text
2374    form, two zic input files tzdata.zi and leapseconds are now
2375    installed by default.  The commands 'zic tzdata.zi' and 'zic -L
2376    leapseconds tzdata.zi' can reproduce the tzdata binary files
2377    without and with leap seconds, respectively.  To prevent these two
2378    new files from being installed, use 'make TZDATA_TEXT=', and to
2379    suppress leap seconds from the tzdata text installation, use 'make
2380    TZDATA_TEXT=tzdata.zi'.
2381
2382    'make BACKWARD=' now suppresses backward-compatibility names
2383    like 'US/Pacific' that are defined in the 'backward' and
2384    'pacificnew' files.
2385
2386    'make check' now works on systems that lack a UTF-8 locale,
2387    or that lack the nsgmls program.  Set UTF8_LOCALE to configure
2388    the name of a UTF-8 locale, if you have one.
2389
2390    Y2K runtime checks are no longer enabled by default.  Add
2391    -DDEPRECATE_TWO_DIGIT_YEARS to CFLAGS to enable them, instead of
2392    adding -DNO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
2393    to disable them.  (New name suggested by Brian Inglis.)
2394
2395    The build procedure for zdump now works on AIX 7.1.
2396    (Problem reported by Kees Dekker.)
2397
2398  Changes to code
2399
2400    zic and the reference runtime now reject multiple leap seconds
2401    within 28 days of each other, or leap seconds before the Epoch.
2402    As a result, support for double leap seconds, which was
2403    obsolescent and undocumented, has been removed.  Double leap
2404    seconds were an error in the C89 standard; they have never existed
2405    in civil timekeeping.  (Thanks to Robert Elz and Bradley White for
2406    noticing glitches in the code that uncovered this problem.)
2407
2408    zic now warns about use of the obsolescent and undocumented -y
2409    option, and about use of the obsolescent TYPE field of Rule lines.
2410
2411    zic now allows unambiguous abbreviations like "Sa" and "Su" for
2412    weekdays; formerly it rejected them due to a bug.  Conversely, zic
2413    no longer considers non-prefixes to be abbreviations; for example,
2414    it no longer accepts "lF" as an abbreviation for "lastFriday".
2415    Also, zic warns about the undocumented usage with a "last-"
2416    prefix, e.g., "last-Fri".
2417
2418    Similarly, zic now accepts the unambiguous abbreviation "L" for
2419    "Link" in ordinary context and for "Leap" in leap-second context.
2420    Conversely, zic no longer accepts non-prefixes such as "La" as
2421    abbreviations for words like "Leap".
2422
2423    zic no longer accepts leap second lines in ordinary input, or
2424    ordinary lines in leap second input.  Formerly, zic sometimes
2425    warned about this undocumented usage and handled it incorrectly.
2426
2427    The new macro HAVE_TZNAME governs whether the tzname external
2428    variable is exported, instead of USG_COMPAT.  USG_COMPAT now
2429    governs only the external variables "timezone" and "daylight".
2430    This change is needed because the three variables are not in the
2431    same category: although POSIX requires tzname, it specifies the
2432    other two variables as optional.  Also, USG_COMPAT is now 1 or 0:
2433    if not defined, the code attempts to guess it from other macros.
2434
2435    localtime.c and difftime.c no longer require stdio.h, and .c files
2436    other than zic.c no longer require sys/wait.h.
2437
2438    zdump.c no longer assumes snprintf.  (Reported by Jonathan Leffler.)
2439
2440    Calculation of time_t extrema works around a bug in GCC 4.8.4
2441    (Reported by Stan Shebs and Joseph Myers.)
2442
2443    zic.c no longer mistranslates formats of line numbers in non-English
2444    locales.  (Problem reported by Benno Schulenberg.)
2445
2446    Several minor changes have been made to the code to make it a
2447    bit easier to port to MS-Windows and Solaris.  (Thanks to Kees
2448    Dekker for reporting the problems.)
2449
2450  Changes to documentation and commentary
2451
2452    The two new files 'theory.html' and 'calendars' contain the
2453    contents of the removed file 'Theory'.  The goal is to document
2454    tzdb theory more accessibly.
2455
2456    The zic man page now documents abbreviation rules.
2457
2458    tz-link.htm now covers how to apply tzdata changes to clients.
2459    (Thanks to Jorge Fábregas for the AIX link.)  It also mentions MySQL.
2460
2461    The leap-seconds.list URL has been updated to something that is
2462    more reliable for tzdb.  (Thanks to Tim Parenti and Brian Inglis.)
2463
2464Release 2017b - 2017-03-17 07:30:38 -0700
2465
2466  Briefly: Haiti has resumed DST.
2467
2468  Changes to past and future timestamps
2469
2470    Haiti resumed observance of DST in 2017.  (Thanks to Steffen Thorsen.)
2471
2472  Changes to past timestamps
2473
2474    Liberia changed from -004430 to +00 on 1972-01-07, not 1972-05-01.
2475
2476    Use "MMT" to abbreviate Liberia's time zone before 1972, as "-004430"
2477    is one byte over the POSIX limit.  (Problem reported by Derick Rethans.)
2478
2479  Changes to code
2480
2481    The reference localtime implementation now falls back on the
2482    current US daylight-saving transition rules rather than the
2483    1987-2006 rules.  This fallback occurs only when (1) the TZ
2484    environment variable has a value like "AST4ADT" that asks
2485    for daylight saving time but does not specify the rules, (2) there
2486    is no file by that name, and (3) the TZDEFRULES file cannot be
2487    loaded.  (Thanks to Tom Lane.)
2488
2489
2490Release 2017a - 2017-02-28 00:05:36 -0800
2491
2492  Briefly: Southern Chile moves from -04/-03 to -03, and Mongolia
2493  discontinues DST.
2494
2495  Changes to future timestamps
2496
2497    Mongolia no longer observes DST.  (Thanks to Ganbold Tsagaankhuu.)
2498
2499    Chile's Region of Magallanes moves from -04/-03 to -03 year-round.
2500    Its clocks diverge from America/Santiago starting 2017-05-13 at
2501    23:00, hiving off a new zone America/Punta_Arenas.  Although the
2502    Chilean government says this change expires in May 2019, for now
2503    assume it's permanent.  (Thanks to Juan Correa and Deborah
2504    Goldsmith.)  This also affects Antarctica/Palmer.
2505
2506  Changes to past timestamps
2507
2508    Fix many entries for historical timestamps for Europe/Madrid
2509    before 1979, to agree with tables compiled by Pere Planesas of the
2510    National Astronomical Observatory of Spain.  As a side effect,
2511    this changes some timestamps for Africa/Ceuta before 1929, which
2512    are probably guesswork anyway.  (Thanks to Steve Allen and
2513    Pierpaolo Bernardi for the heads-ups, and to Michael Deckers for
2514    correcting the 1901 transition.)
2515
2516    Ecuador observed DST from 1992-11-28 to 1993-02-05.
2517    (Thanks to Alois Treindl.)
2518
2519    Asia/Atyrau and Asia/Oral were at +03 (not +04) before 1930-06-21.
2520    (Thanks to Stepan Golosunov.)
2521
2522  Changes to past and future time zone abbreviations
2523
2524    Switch to numeric time zone abbreviations for South America, as
2525    part of the ongoing project of removing invented abbreviations.
2526    This avoids the need to invent an abbreviation for the new Chilean
2527    new zone.  Similarly, switch from invented to numeric time zone
2528    abbreviations for Afghanistan, American Samoa, the Azores,
2529    Bangladesh, Bhutan, the British Indian Ocean Territory, Brunei,
2530    Cape Verde, Chatham Is, Christmas I, Cocos (Keeling) Is, Cook Is,
2531    Dubai, East Timor, Eucla, Fiji, French Polynesia, Greenland,
2532    Indochina, Iran, Iraq, Kiribati, Lord Howe, Macquarie, Malaysia,
2533    the Maldives, Marshall Is, Mauritius, Micronesia, Mongolia,
2534    Myanmar, Nauru, Nepal, New Caledonia, Niue, Norfolk I, Palau,
2535    Papua New Guinea, the Philippines, Pitcairn, Qatar, Réunion, St
2536    Pierre & Miquelon, Samoa, Saudi Arabia, Seychelles, Singapore,
2537    Solomon Is, Tokelau, Tuvalu, Wake, Vanuatu, Wallis & Futuna, and
2538    Xinjiang; for 20-minute daylight saving time in Ghana before 1943;
2539    for half-hour daylight saving time in Belize before 1944 and in
2540    the Dominican Republic before 1975; and for Canary Islands before
2541    1946, for Guinea-Bissau before 1975, for Iceland before 1969, for
2542    Indian Summer Time before 1942, for Indonesia before around 1964,
2543    for Kenya before 1960, for Liberia before 1973, for Madeira before
2544    1967, for Namibia before 1943, for the Netherlands in 1937-9, for
2545    Pakistan before 1971, for Western Sahara before 1977, and for
2546    Zaporozhye in 1880-1924.
2547
2548    For Alaska time from 1900 through 1967, instead of "CAT" use the
2549    abbreviation "AST", the abbreviation commonly used at the time
2550    (Atlantic Standard Time had not been standardized yet).  Use "AWT"
2551    and "APT" instead of the invented abbreviations "CAWT" and "CAPT".
2552
2553    Use "CST" and "CDT" instead of invented abbreviations for Macau
2554    before 1999 and Taiwan before 1938, and use "JST" instead of the
2555    invented abbreviation "JCST" for Japan and Korea before 1938.
2556
2557  Change to database entry category
2558
2559    Move the Pacific/Johnston link from 'australasia' to 'backward',
2560    since Johnston is now uninhabited.
2561
2562  Changes to code
2563
2564    zic no longer mishandles some transitions in January 2038 when it
2565    attempts to work around Qt bug 53071.  This fixes a bug affecting
2566    Pacific/Tongatapu that was introduced in zic 2016e.  localtime.c
2567    now contains a workaround, useful when loading a file generated by
2568    a buggy zic.  (Problem and localtime.c fix reported by Bradley
2569    White.)
2570
2571    zdump -i now outputs non-hour numeric time zone abbreviations
2572    without a colon, e.g., "+0530" rather than "+05:30".  This agrees
2573    with zic %z and with common practice, and simplifies auditing of
2574    zdump output.
2575
2576    zdump is now buildable again with -DUSE_LTZ=0.
2577    (Problem reported by Joseph Myers.)
2578
2579    zdump.c now always includes private.h, to avoid code duplication
2580    with private.h.  (Problem reported by Kees Dekker.)
2581
2582    localtime.c no longer mishandles early or late timestamps
2583    when TZ is set to a POSIX-style string that specifies DST.
2584    (Problem reported by Kees Dekker.)
2585
2586    date and strftime now cause %z to generate "-0000" instead of
2587    "+0000" when the UT offset is zero and the time zone abbreviation
2588    begins with "-".
2589
2590  Changes to documentation and commentary
2591
2592    The 'Theory' file now better documents choice of historical time
2593    zone abbreviations.  (Problems reported by Michael Deckers.)
2594
2595    tz-link.htm now covers leap smearing, which is popular in clouds.
2596
2597
2598Release 2016j - 2016-11-22 23:17:13 -0800
2599
2600  Briefly: Saratov, Russia moves from +03 to +04 on 2016-12-04.
2601
2602  Changes to future timestamps
2603
2604    Saratov, Russia switches from +03 to +04 on 2016-12-04 at 02:00.
2605    This hives off a new zone Europe/Saratov from Europe/Volgograd.
2606    (Thanks to Yuri Konotopov and Stepan Golosunov.)
2607
2608  Changes to past timestamps
2609
2610    The new zone Asia/Atyrau for Atyraū Region, Kazakhstan, is like
2611    Asia/Aqtau except it switched from +05/+06 to +04/+05 in spring
2612    1999, not fall 1994.  (Thanks to Stepan Golosunov.)
2613
2614  Changes to past time zone abbreviations
2615
2616    Asia/Gaza and Asia/Hebron now use "EEST", not "EET", to denote
2617    summer time before 1948.  The old use of "EET" was a typo.
2618
2619  Changes to code
2620
2621    zic no longer mishandles file systems that lack hard links, fixing
2622    bugs introduced in 2016g.  (Problems reported by Tom Lane.)
2623    Also, when the destination already contains symbolic links, zic
2624    should now work better on systems where the 'link' system call
2625    does not follow symbolic links.
2626
2627  Changes to documentation and commentary
2628
2629    tz-link.htm now documents the relationship between release version
2630    numbers and development-repository commit tags.  (Suggested by
2631    Paul Koning.)
2632
2633    The 'Theory' file now documents UT.
2634
2635    iso3166.tab now accents "Curaçao", and commentary now mentions
2636    the names "Cabo Verde" and "Czechia".  (Thanks to Jiří Boháč.)
2637
2638
2639Release 2016i - 2016-11-01 23:19:52 -0700
2640
2641  Briefly: Cyprus split into two time zones on 2016-10-30, and Tonga
2642  reintroduces DST on 2016-11-06.
2643
2644  Changes to future timestamps
2645
2646    Pacific/Tongatapu begins DST on 2016-11-06 at 02:00, ending on
2647    2017-01-15 at 03:00.  Assume future observances in Tonga will be
2648    from the first Sunday in November through the third Sunday in
2649    January, like Fiji.  (Thanks to Pulu ʻAnau.)  Switch to numeric
2650    time zone abbreviations for this zone.
2651
2652  Changes to past and future timestamps
2653
2654    Northern Cyprus is now +03 year round, causing a split in Cyprus
2655    time zones starting 2016-10-30 at 04:00.  This creates a zone
2656    Asia/Famagusta.  (Thanks to Even Scharning and Matt Johnson.)
2657
2658    Antarctica/Casey switched from +08 to +11 on 2016-10-22.
2659    (Thanks to Steffen Thorsen.)
2660
2661  Changes to past timestamps
2662
2663    Several corrections were made for pre-1975 timestamps in Italy.
2664    These affect Europe/Malta, Europe/Rome, Europe/San_Marino, and
2665    Europe/Vatican.
2666
2667    First, the 1893-11-01 00:00 transition in Italy used the new UT
2668    offset (+01), not the old (+00:49:56).  (Thanks to Michael
2669    Deckers.)
2670
2671    Second, rules for daylight saving in Italy were changed to agree
2672    with Italy's National Institute of Metrological Research (INRiM)
2673    except for 1944, as follows (thanks to Pierpaolo Bernardi, Brian
2674    Inglis, and Michael Deckers):
2675
2676      The 1916-06-03 transition was at 24:00, not 00:00.
2677
2678      The 1916-10-01, 1919-10-05, and 1920-09-19 transitions were at
2679      00:00, not 01:00.
2680
2681      The 1917-09-30 and 1918-10-06 transitions were at 24:00, not
2682      01:00.
2683
2684      The 1944-09-17 transition was at 03:00, not 01:00.  This
2685      particular change is taken from Italian law as INRiM's table,
2686      (which says 02:00) appears to have a typo here.  Also, keep the
2687      1944-04-03 transition for Europe/Rome, as Rome was controlled by
2688      Germany then.
2689
2690      The 1967-1970 and 1972-1974 fallback transitions were at 01:00,
2691      not 00:00.
2692
2693  Changes to code
2694
2695    The code should now be buildable on AmigaOS merely by setting the
2696    appropriate Makefile variables.  (From a patch by Carsten Larsen.)
2697
2698
2699Release 2016h - 2016-10-19 23:17:57 -0700
2700
2701  Changes to future timestamps
2702
2703    Asia/Gaza and Asia/Hebron end DST on 2016-10-29 at 01:00, not
2704    2016-10-21 at 00:00.  (Thanks to Sharef Mustafa.)  Predict that
2705    future fall transitions will be on the last Saturday of October
2706    at 01:00, which is consistent with predicted spring transitions
2707    on the last Saturday of March.  (Thanks to Tim Parenti.)
2708
2709  Changes to past timestamps
2710
2711    In Turkey, transitions in 1986-1990 were at 01:00 standard time
2712    not at 02:00, and the spring 1994 transition was on March 20, not
2713    March 27.  (Thanks to Kıvanç Yazan.)
2714
2715  Changes to past and future time zone abbreviations
2716
2717    Asia/Colombo now uses numeric time zone abbreviations like "+0530"
2718    instead of alphabetic ones like "IST" and "LKT".  Various
2719    English-language sources use "IST", "LKT" and "SLST", with no
2720    working consensus.  (Usage of "SLST" mentioned by Sadika
2721    Sumanapala.)
2722
2723  Changes to code
2724
2725    zic no longer mishandles relativizing file names when creating
2726    symbolic links like /etc/localtime, when these symbolic links
2727    are outside the usual directory hierarchy.  This fixes a bug
2728    introduced in 2016g.  (Problem reported by Andreas Stieger.)
2729
2730  Changes to build procedure
2731
2732    New rules 'traditional_tarballs' and 'traditional_signatures' for
2733    building just the traditional-format distribution.  (Requested by
2734    Deborah Goldsmith.)
2735
2736    The file 'version' is now put into the tzdata tarball too.
2737    (Requested by Howard Hinnant.)
2738
2739  Changes to documentation and commentary
2740
2741    The 'Theory' file now has a section on interface stability.
2742    (Requested by Paul Koning.)  It also mentions features like
2743    tm_zone and localtime_rz that have long been supported by the
2744    reference code.
2745
2746    tz-link.htm has improved coverage of time zone boundaries suitable
2747    for geolocation.  (Thanks to heads-ups from Evan Siroky and Matt
2748    Johnson.)
2749
2750    The US commentary now mentions Allen and the "day of two noons".
2751
2752    The Fiji commentary mentions the government's 2016-10-03 press
2753    release.  (Thanks to Raymond Kumar.)
2754
2755
2756Release 2016g - 2016-09-13 08:56:38 -0700
2757
2758  Changes to future timestamps
2759
2760    Turkey switched from EET/EEST (+02/+03) to permanent +03,
2761    effective 2016-09-07.  (Thanks to Burak AYDIN.)  Use "+03" rather
2762    than an invented abbreviation for the new time.
2763
2764    New leap second 2016-12-31 23:59:60 UTC as per IERS Bulletin C 52.
2765    (Thanks to Tim Parenti.)
2766
2767  Changes to past timestamps
2768
2769    For America/Los_Angeles, spring-forward transition times have been
2770    corrected from 02:00 to 02:01 in 1948, and from 02:00 to 01:00 in
2771    1950-1966.
2772
2773    For zones using Soviet time on 1919-07-01, transitions to UT-based
2774    time were at 00:00 UT, not at 02:00 local time.  The affected
2775    zones are Europe/Kirov, Europe/Moscow, Europe/Samara, and
2776    Europe/Ulyanovsk.  (Thanks to Alexander Belopolsky.)
2777
2778  Changes to past and future time zone abbreviations
2779
2780    The Factory zone now uses the time zone abbreviation -00 instead
2781    of a long English-language string, as -00 is now the normal way to
2782    represent an undefined time zone.
2783
2784    Several zones in Antarctica and the former Soviet Union, along
2785    with zones intended for ships at sea that cannot use POSIX TZ
2786    strings, now use numeric time zone abbreviations instead of
2787    invented or obsolete alphanumeric abbreviations.  The affected
2788    zones are Antarctica/Casey, Antarctica/Davis,
2789    Antarctica/DumontDUrville, Antarctica/Mawson, Antarctica/Rothera,
2790    Antarctica/Syowa, Antarctica/Troll, Antarctica/Vostok,
2791    Asia/Anadyr, Asia/Ashgabat, Asia/Baku, Asia/Bishkek, Asia/Chita,
2792    Asia/Dushanbe, Asia/Irkutsk, Asia/Kamchatka, Asia/Khandyga,
2793    Asia/Krasnoyarsk, Asia/Magadan, Asia/Omsk, Asia/Sakhalin,
2794    Asia/Samarkand, Asia/Srednekolymsk, Asia/Tashkent, Asia/Tbilisi,
2795    Asia/Ust-Nera, Asia/Vladivostok, Asia/Yakutsk, Asia/Yekaterinburg,
2796    Asia/Yerevan, Etc/GMT-14, Etc/GMT-13, Etc/GMT-12, Etc/GMT-11,
2797    Etc/GMT-10, Etc/GMT-9, Etc/GMT-8, Etc/GMT-7, Etc/GMT-6, Etc/GMT-5,
2798    Etc/GMT-4, Etc/GMT-3, Etc/GMT-2, Etc/GMT-1, Etc/GMT+1, Etc/GMT+2,
2799    Etc/GMT+3, Etc/GMT+4, Etc/GMT+5, Etc/GMT+6, Etc/GMT+7, Etc/GMT+8,
2800    Etc/GMT+9, Etc/GMT+10, Etc/GMT+11, Etc/GMT+12, Europe/Kaliningrad,
2801    Europe/Minsk, Europe/Samara, Europe/Volgograd, and
2802    Indian/Kerguelen.  For Europe/Moscow the invented abbreviation MSM
2803    was replaced by +05, whereas MSK and MSD were kept as they are not
2804    our invention and are widely used.
2805
2806  Changes to zone names
2807
2808    Rename Asia/Rangoon to Asia/Yangon, with a backward compatibility link.
2809    (Thanks to David Massoud.)
2810
2811  Changes to code
2812
2813    zic no longer generates binary files containing POSIX TZ-like
2814    strings that disagree with the local time type after the last
2815    explicit transition in the data.  This fixes a bug with
2816    Africa/Casablanca and Africa/El_Aaiun in some year-2037 timestamps
2817    on the reference platform.  (Thanks to Alexander Belopolsky for
2818    reporting the bug and suggesting a way forward.)
2819
2820    If the installed localtime and/or posixrules files are symbolic
2821    links, zic now keeps them symbolic links when updating them, for
2822    compatibility with platforms like OpenSUSE where other programs
2823    configure these files as symlinks.
2824
2825    zic now avoids hard linking to symbolic links, avoids some
2826    unnecessary mkdir and stat system calls, and uses shorter file
2827    names internally.
2828
2829    zdump has a new -i option to generate transitions in a
2830    smaller but still human-readable format.  This option is
2831    experimental, and the output format may change in future versions.
2832    (Thanks to Jon Skeet for suggesting that an option was needed,
2833    and thanks to Tim Parenti and Chris Rovick for further comments.)
2834
2835  Changes to build procedure
2836
2837    An experimental distribution format is available, in addition
2838    to the traditional format which will continue to be distributed.
2839    The new format is a tarball tzdb-VERSION.tar.lz with signature
2840    file tzdb-VERSION.tar.lz.asc.  It unpacks to a top-level directory
2841    tzdb-VERSION containing the code and data of the traditional
2842    two-tarball format, along with extra data that may be useful.
2843    (Thanks to Antonio Diaz Diaz, Oscar van Vlijmen, and many others
2844    for comments about the experimental format.)
2845
2846    The release version number is now more accurate in the usual case
2847    where releases are built from a Git repository.  For example, if
2848    23 commits and some working-file changes have been made since
2849    release 2016g, the version number is now something like
2850    '2016g-23-g50556e3-dirty' instead of the misleading '2016g'.
2851    Tagged releases use the same version number format as before,
2852    e.g., '2016g'.  To support the more accurate version number, its
2853    specification has moved from a line in the Makefile to a new
2854    source file 'version'.
2855
2856    The experimental distribution contains a file to2050.tzs that
2857    contains what should be the output of 'zdump -i -c 2050' on
2858    primary zones.  If this file is available, 'make check' now checks
2859    that zdump generates this output.
2860
2861    'make check_web' now works on Fedora-like distributions.
2862
2863  Changes to documentation and commentary
2864
2865    tzfile.5 now documents the new restriction on POSIX TZ-like
2866    strings that is now implemented by zic.
2867
2868    Comments now cite URLs for some 1917-1921 Russian DST decrees.
2869    (Thanks to Alexander Belopolsky.)
2870
2871    tz-link.htm mentions JuliaTime (thanks to Curtis Vogt) and Time4J
2872    (thanks to Meno Hochschild) and ThreeTen-Extra, and its
2873    description of Java 8 has been brought up to date (thanks to
2874    Stephen Colebourne).  Its description of local time on Mars has
2875    been updated to match current practice, and URLs have been updated
2876    and some obsolete ones removed.
2877
2878
2879Release 2016f - 2016-07-05 16:26:51 +0200
2880
2881  Changes affecting future timestamps
2882
2883    The Egyptian government changed its mind on short notice, and
2884    Africa/Cairo will not introduce DST starting 2016-07-07 after all.
2885    (Thanks to Mina Samuel.)
2886
2887    Asia/Novosibirsk switches from +06 to +07 on 2016-07-24 at 02:00.
2888    (Thanks to Stepan Golosunov.)
2889
2890  Changes to past and future timestamps
2891
2892    Asia/Novokuznetsk and Asia/Novosibirsk now use numeric time zone
2893    abbreviations instead of invented ones.
2894
2895  Changes affecting past timestamps
2896
2897    Europe/Minsk's 1992-03-29 spring-forward transition was at 02:00 not 00:00.
2898    (Thanks to Stepan Golosunov.)
2899
2900
2901Release 2016e - 2016-06-14 08:46:16 -0700
2902
2903  Changes affecting future timestamps
2904
2905    Africa/Cairo observes DST in 2016 from July 7 to the end of October.
2906    Guess October 27 and 24:00 transitions.  (Thanks to Steffen Thorsen.)
2907    For future years, guess April's last Thursday to October's last
2908    Thursday except for Ramadan.
2909
2910  Changes affecting past timestamps
2911
2912    Locations while uninhabited now use '-00', not 'zzz', as a
2913    placeholder time zone abbreviation.  This is inspired by Internet
2914    RFC 3339 and is more consistent with numeric time zone
2915    abbreviations already used elsewhere.  The change affects several
2916    arctic and antarctic locations, e.g., America/Cambridge_Bay before
2917    1920 and Antarctica/Troll before 2005.
2918
2919    Asia/Baku's 1992-09-27 transition from +04 (DST) to +04 (non-DST) was
2920    at 03:00, not 23:00 the previous day.  (Thanks to Michael Deckers.)
2921
2922  Changes to code
2923
2924    zic now outputs a dummy transition at time 2**31 - 1 in zones
2925    whose POSIX-style TZ strings contain a '<'.  This mostly works
2926    around Qt bug 53071 <https://bugreports.qt.io/browse/QTBUG-53071>.
2927    (Thanks to Zhanibek Adilbekov for reporting the Qt bug.)
2928
2929  Changes affecting documentation and commentary
2930
2931    tz-link.htm says why governments should give plenty of notice for
2932    time zone or DST changes, and refers to Matt Johnson's blog post.
2933
2934    tz-link.htm mentions Tzdata for Elixir.  (Thanks to Matt Johnson.)
2935
2936
2937Release 2016d - 2016-04-17 22:50:29 -0700
2938
2939  Changes affecting future timestamps
2940
2941    America/Caracas switches from -0430 to -04 on 2016-05-01 at 02:30.
2942    (Thanks to Alexander Krivenyshev for the heads-up.)
2943
2944    Asia/Magadan switches from +10 to +11 on 2016-04-24 at 02:00.
2945    (Thanks to Alexander Krivenyshev and Matt Johnson.)
2946
2947    New zone Asia/Tomsk, split off from Asia/Novosibirsk.  It covers
2948    Tomsk Oblast, Russia, which switches from +06 to +07 on 2016-05-29
2949    at 02:00.  (Thanks to Stepan Golosunov.)
2950
2951  Changes affecting past timestamps
2952
2953    New zone Europe/Kirov, split off from Europe/Volgograd.  It covers
2954    Kirov Oblast, Russia, which switched from +04/+05 to +03/+04 on
2955    1989-03-26 at 02:00, roughly a year after Europe/Volgograd made
2956    the same change.  (Thanks to Stepan Golosunov.)
2957
2958    Russia and nearby locations had daylight-saving transitions on
2959    1992-03-29 at 02:00 and 1992-09-27 at 03:00, instead of on
2960    1992-03-28 at 23:00 and 1992-09-26 at 23:00.  (Thanks to Stepan
2961    Golosunov.)
2962
2963    Many corrections to historical time in Kazakhstan from 1991
2964    through 2005.  (Thanks to Stepan Golosunov.)  Replace Kazakhstan's
2965    invented time zone abbreviations with numeric abbreviations.
2966
2967  Changes to commentary
2968
2969    Mention Internet RFCs 7808 (TZDIST) and 7809 (CalDAV time zone references).
2970
2971
2972Release 2016c - 2016-03-23 00:51:27 -0700
2973
2974  Changes affecting future timestamps
2975
2976    Azerbaijan no longer observes DST.  (Thanks to Steffen Thorsen.)
2977
2978    Chile reverts from permanent to seasonal DST.  (Thanks to Juan
2979    Correa for the heads-up, and to Tim Parenti for corrections.)
2980    Guess that future transitions are August's and May's second
2981    Saturdays at 24:00 mainland time.  Also, call the period from
2982    2014-09-07 through 2016-05-14 daylight saving time instead of
2983    standard time, as that seems more appropriate now.
2984
2985  Changes affecting past timestamps
2986
2987    Europe/Kaliningrad and Europe/Vilnius changed from +03/+04 to
2988    +02/+03 on 1989-03-26, not 1991-03-31.  Europe/Volgograd changed
2989    from +04/+05 to +03/+04 on 1988-03-27, not 1989-03-26.
2990    (Thanks to Stepan Golosunov.)
2991
2992  Changes to commentary
2993
2994    Several updates and URLs for historical and proposed Russian changes.
2995    (Thanks to Stepan Golosunov, Matt Johnson, and Alexander Krivenyshev.)
2996
2997
2998Release 2016b - 2016-03-12 17:30:14 -0800
2999
3000  Compatibility note
3001
3002    Starting with release 2016b, some data entries cause zic implementations
3003    derived from tz releases 2005j through 2015e to issue warnings like
3004    "time zone abbreviation differs from POSIX standard (+03)".
3005    These warnings should not otherwise affect zic's output and can safely be
3006    ignored on today's platforms, as the warnings refer to a restriction in
3007    POSIX.1-1988 that was removed in POSIX.1-2001.  One way to suppress the
3008    warnings is to upgrade to zic derived from tz releases 2015f and later.
3009
3010  Changes affecting future timestamps
3011
3012    New zones Europe/Astrakhan and Europe/Ulyanovsk for Astrakhan and
3013    Ulyanovsk Oblasts, Russia, both of which will switch from +03 to +04 on
3014    2016-03-27 at 02:00 local time.  They need distinct zones since their
3015    post-1970 histories disagree.  New zone Asia/Barnaul for Altai Krai and
3016    Altai Republic, Russia, which will switch from +06 to +07 on the same date
3017    and local time.  The Astrakhan change is already official; the others have
3018    passed the first reading in the State Duma and are extremely likely.
3019    Also, Asia/Sakhalin moves from +10 to +11 on 2016-03-27 at 02:00.
3020    (Thanks to Alexander Krivenyshev for the heads-up, and to Matt Johnson
3021    and Stepan Golosunov for followup.)
3022
3023    As a trial of a new system that needs less information to be made up,
3024    the new zones use numeric time zone abbreviations like "+04"
3025    instead of invented abbreviations like "ASTT".
3026
3027    Haiti will not observe DST in 2016.  (Thanks to Jean Antoine via
3028    Steffen Thorsen.)
3029
3030    Palestine's spring-forward transition on 2016-03-26 is at 01:00, not 00:00.
3031    (Thanks to Hannah Kreitem.) Guess future transitions will be March's last
3032    Saturday at 01:00, not March's last Friday at 24:00.
3033
3034  Changes affecting past timestamps
3035
3036    Europe/Chisinau observed DST during 1990, and switched from +04 to
3037    +03 at 1990-05-06 02:00, instead of switching from +03 to +02.
3038    (Thanks to Stepan Golosunov.)
3039
3040    1991 abbreviations in Europe/Samara should be SAMT/SAMST, not
3041    KUYT/KUYST.  (Thanks to Stepan Golosunov.)
3042
3043  Changes to code
3044
3045    tzselect's diagnostics and checking, and checktab.awk's checking,
3046    have been improved.  (Thanks to J William Piggott.)
3047
3048    tzcode now builds under MinGW.  (Thanks to Ian Abbott and Esben Haabendal.)
3049
3050    tzselect now tests Julian-date TZ settings more accurately.
3051    (Thanks to J William Piggott.)
3052
3053  Changes to commentary
3054
3055    Comments in zone tables have been improved.  (Thanks to J William Piggott.)
3056
3057    tzselect again limits its menu comments so that menus fit on a
3058    24×80 alphanumeric display.
3059
3060    A new web page tz-how-to.html.  (Thanks to Bill Seymour.)
3061
3062    In the Theory file, the description of possible time zone abbreviations in
3063    tzdata has been cleaned up, as the old description was unclear and
3064    inconsistent.  (Thanks to Alain Mouette for reporting the problem.)
3065
3066
3067Release 2016a - 2016-01-26 23:28:02 -0800
3068
3069  Changes affecting future timestamps
3070
3071    America/Cayman will not observe daylight saving this year after all.
3072    Revert our guess that it would.  (Thanks to Matt Johnson.)
3073
3074    Asia/Chita switches from +0800 to +0900 on 2016-03-27 at 02:00.
3075    (Thanks to Alexander Krivenyshev.)
3076
3077    Asia/Tehran now has DST predictions for the year 2038 and later,
3078    to be March 21 00:00 to September 21 00:00.  This is likely better
3079    than predicting no DST, albeit off by a day every now and then.
3080
3081  Changes affecting past and future timestamps
3082
3083    America/Metlakatla switched from PST all year to AKST/AKDT on
3084    2015-11-01 at 02:00.  (Thanks to Steffen Thorsen.)
3085
3086    America/Santa_Isabel has been removed, and replaced with a
3087    backward compatibility link to America/Tijuana.  Its contents were
3088    apparently based on a misreading of Mexican legislation.
3089
3090  Changes affecting past timestamps
3091
3092    Asia/Karachi's two transition times in 2002 were off by a minute.
3093    (Thanks to Matt Johnson.)
3094
3095  Changes affecting build procedure
3096
3097    An installer can now combine leap seconds with use of the backzone file,
3098    e.g., with 'make PACKRATDATA=backzone REDO=posix_right zones'.
3099    The old 'make posix_packrat' rule is now marked as obsolescent.
3100    (Thanks to Ian Abbott for an initial implementation.)
3101
3102  Changes affecting documentation and commentary
3103
3104    A new file LICENSE makes it easier to see that the code and data
3105    are mostly public-domain.  (Thanks to James Knight.)  The three
3106    non-public-domain files now use the current (3-clause) BSD license
3107    instead of older versions of that license.
3108
3109    tz-link.htm mentions the BDE library (thanks to Andrew Paprocki),
3110    CCTZ (thanks to Tim Parenti), TimeJones.com, and has a new section
3111    on editing tz source files (with a mention of Sublime zoneinfo,
3112    thanks to Gilmore Davidson).
3113
3114    The Theory and asia files now mention the 2015 book "The Global
3115    Transformation of Time, 1870-1950", and cite a couple of reviews.
3116
3117    The America/Chicago entry now documents the informal use of US
3118    central time in Fort Pierre, South Dakota.  (Thanks to Rick
3119    McDermid, Matt Johnson, and Steve Jones.)
3120
3121
3122Release 2015g - 2015-10-01 00:39:51 -0700
3123
3124  Changes affecting future timestamps
3125
3126    Turkey's 2015 fall-back transition is scheduled for Nov. 8, not Oct. 25.
3127    (Thanks to Fatih.)
3128
3129    Norfolk moves from +1130 to +1100 on 2015-10-04 at 02:00 local time.
3130    (Thanks to Alexander Krivenyshev.)
3131
3132    Fiji's 2016 fall-back transition is scheduled for January 17, not 24.
3133    (Thanks to Ken Rylander.)
3134
3135    Fort Nelson, British Columbia will not fall back on 2015-11-01.  It has
3136    effectively been on MST (-0700) since it advanced its clocks on 2015-03-08.
3137    New zone America/Fort_Nelson.  (Thanks to Matt Johnson.)
3138
3139  Changes affecting past timestamps
3140
3141    Norfolk observed DST from 1974-10-27 02:00 to 1975-03-02 02:00.
3142
3143  Changes affecting code
3144
3145    localtime no longer mishandles America/Anchorage after 2037.
3146    (Thanks to Bradley White for reporting the bug.)
3147
3148    On hosts with signed 32-bit time_t, localtime no longer mishandles
3149    Pacific/Fiji after 2038-01-16 14:00 UTC.
3150
3151    The localtime module allows the variables 'timezone', 'daylight',
3152    and 'altzone' to be in common storage shared with other modules,
3153    and declares them in case the system <time.h> does not.
3154    (Problems reported by Kees Dekker.)
3155
3156    On platforms with tm_zone, strftime.c now assumes it is not NULL.
3157    This simplifies the code and is consistent with zdump.c.
3158    (Problem reported by Christos Zoulas.)
3159
3160  Changes affecting documentation
3161
3162   The tzfile man page now documents that transition times denote the
3163   starts (not the ends) of the corresponding time periods.
3164   (Ambiguity reported by Bill Seymour.)
3165
3166
3167Release 2015f - 2015-08-10 18:06:56 -0700
3168
3169  Changes affecting future timestamps
3170
3171    North Korea switches to +0830 on 2015-08-15.  (Thanks to Steffen Thorsen.)
3172    The abbreviation remains "KST".  (Thanks to Robert Elz.)
3173
3174    Uruguay no longer observes DST.  (Thanks to Steffen Thorsen
3175    and Pablo Camargo.)
3176
3177  Changes affecting past and future timestamps
3178
3179    Moldova starts and ends DST at 00:00 UTC, not at 01:00 UTC.
3180    (Thanks to Roman Tudos.)
3181
3182  Changes affecting data format and code
3183
3184    zic's '-y YEARISTYPE' option is no longer documented.  The TYPE
3185    field of a Rule line should now be '-'; the old values 'even',
3186    'odd', 'uspres', 'nonpres', 'nonuspres' were already undocumented.
3187    Although the implementation has not changed, these features do not
3188    work in the default installation, they are not used in the data,
3189    and they are now considered obsolescent.
3190
3191    zic now checks that two rules don't take effect at the same time.
3192    (Thanks to Jon Skeet and Arthur David Olson.)  Constraints on
3193    simultaneity are now documented.
3194
3195    The two characters '%z' in a zone format now stand for the UT
3196    offset, e.g., '-07' for seven hours behind UT and '+0530' for
3197    five hours and thirty minutes ahead.  This better supports time
3198    zone abbreviations conforming to POSIX.1-2001 and later.
3199
3200  Changes affecting installed data files
3201
3202    Comments for America/Halifax and America/Glace_Bay have been improved.
3203    (Thanks to Brian Inglis.)
3204
3205    Data entries have been simplified for Atlantic/Canary, Europe/Simferopol,
3206    Europe/Sofia, and Europe/Tallinn.  This yields slightly smaller
3207    installed data files for Europe/Simferopol and Europe/Tallinn.
3208    It does not affect timestamps.  (Thanks to Howard Hinnant.)
3209
3210  Changes affecting code
3211
3212    zdump and zic no longer warn about valid time zone abbreviations
3213    like '-05'.
3214
3215    Some Visual Studio 2013 warnings have been suppressed.
3216    (Thanks to Kees Dekker.)
3217
3218    'date' no longer sets the time of day and its -a, -d, -n and -t
3219    options have been removed.  Long obsolescent, the implementation
3220    of these features had porting problems.  Builders no longer need
3221    to configure HAVE_ADJTIME, HAVE_SETTIMEOFDAY, or HAVE_UTMPX_H.
3222    (Thanks to Kees Dekker for pointing out the problem.)
3223
3224  Changes affecting documentation
3225
3226    The Theory file mentions naming issues earlier, as these seem to be
3227    poorly publicized (thanks to Gilmore Davidson for reporting the problem).
3228
3229    tz-link.htm mentions Time Zone Database Parser (thanks to Howard Hinnant).
3230
3231    Mention that Herbert Samuel introduced the term "Summer Time".
3232
3233
3234Release 2015e - 2015-06-13 10:56:02 -0700
3235
3236  Changes affecting future timestamps
3237
3238    Morocco will suspend DST from 2015-06-14 03:00 through 2015-07-19 02:00,
3239    not 06-13 and 07-18 as we had guessed.  (Thanks to Milamber.)
3240
3241    Assume Cayman Islands will observe DST starting next year, using US rules.
3242    Although it isn't guaranteed, it is the most likely.
3243
3244  Changes affecting data format
3245
3246    The file 'iso3166.tab' now uses UTF-8, so that its entries can better
3247    spell the names of Åland Islands, Côte d'Ivoire, and Réunion.
3248
3249  Changes affecting code
3250
3251    When displaying data, tzselect converts it to the current locale's
3252    encoding if the iconv command works.  (Problem reported by random832.)
3253
3254    tzselect no longer mishandles Dominica, fixing a bug introduced
3255    in Release 2014f.  (Problem reported by Owen Leibman.)
3256
3257    zic -l no longer fails when compiled with -DTZDEFAULT=\"/etc/localtime\".
3258    This fixes a bug introduced in Release 2014f.
3259    (Problem reported by Leonardo Chiquitto.)
3260
3261
3262Release 2015d - 2015-04-24 08:09:46 -0700
3263
3264  Changes affecting future timestamps
3265
3266    Egypt will not observe DST in 2015 and will consider canceling it
3267    permanently.  For now, assume no DST indefinitely.
3268    (Thanks to Ahmed Nazmy and Tim Parenti.)
3269
3270  Changes affecting past timestamps
3271
3272    America/Whitehorse switched from UT -09 to -08 on 1967-05-28, not
3273    1966-07-01.  Also, Yukon's time zone history is documented better.
3274    (Thanks to Brian Inglis and Dennis Ferguson.)
3275
3276  Change affecting past and future time zone abbreviations
3277
3278    The abbreviations for Hawaii-Aleutian standard and daylight times
3279    have been changed from HAST/HADT to HST/HDT, as per US Government
3280    Printing Office style.  This affects only America/Adak since 1983,
3281    as America/Honolulu was already using the new style.
3282
3283  Changes affecting code
3284
3285   zic has some minor performance improvements.
3286
3287
3288Release 2015c - 2015-04-11 08:55:55 -0700
3289
3290  Changes affecting future timestamps
3291
3292    Egypt's spring-forward transition is at 24:00 on April's last Thursday,
3293    not 00:00 on April's last Friday.  2015's transition will therefore be on
3294    Thursday, April 30 at 24:00, not Friday, April 24 at 00:00.  Similar fixes
3295    apply to 2026, 2037, 2043, etc.  (Thanks to Steffen Thorsen.)
3296
3297  Changes affecting past timestamps
3298
3299    The following changes affect some pre-1991 Chile-related timestamps
3300    in America/Santiago, Antarctica/Palmer, and Pacific/Easter.
3301
3302      The 1910 transition was January 10, not January 1.
3303
3304      The 1918 transition was September 10, not September 1.
3305
3306      The UT -04 time observed from 1932 to 1942 is now considered to
3307      be standard time, not year-round DST.
3308
3309      Santiago observed DST (UT -03) from 1946-07-15 through
3310      1946-08-31, then reverted to standard time, then switched to -05
3311      on 1947-04-01.
3312
3313      Assume transitions before 1968 were at 00:00, since we have no data
3314      saying otherwise.
3315
3316      The spring 1988 transition was 1988-10-09, not 1988-10-02.
3317      The fall 1990 transition was 1990-03-11, not 1990-03-18.
3318
3319      Assume no UT offset change for Pacific/Easter on 1890-01-01,
3320      and omit all transitions on Pacific/Easter from 1942 through 1946
3321      since we have no data suggesting that they existed.
3322
3323    One more zone has been turned into a link, as it differed
3324    from an existing zone only for older timestamps.  As usual,
3325    this change affects UT offsets in pre-1970 timestamps only.
3326    The zone's old contents have been moved to the 'backzone' file.
3327    The affected zone is America/Montreal.
3328
3329  Changes affecting commentary
3330
3331    Mention the TZUpdater tool.
3332
3333    Mention "The Time Now".  (Thanks to Brandon Ramsey.)
3334
3335
3336Release 2015b - 2015-03-19 23:28:11 -0700
3337
3338  Changes affecting future timestamps
3339
3340    Mongolia will start observing DST again this year, from the last
3341    Saturday in March at 02:00 to the last Saturday in September at 00:00.
3342    (Thanks to Ganbold Tsagaankhuu.)
3343
3344    Palestine will start DST on March 28, not March 27.  Also,
3345    correct the fall 2014 transition from September 26 to October 24.
3346    Adjust future predictions accordingly.  (Thanks to Steffen Thorsen.)
3347
3348  Changes affecting past timestamps
3349
3350    The 1982 zone shift in Pacific/Easter has been corrected, fixing a 2015a
3351    regression.  (Thanks to Stuart Bishop for reporting the problem.)
3352
3353    Some more zones have been turned into links, when they differed
3354    from existing zones only for older timestamps.  As usual,
3355    these changes affect UT offsets in pre-1970 timestamps only.
3356    Their old contents have been moved to the 'backzone' file.
3357    The affected zones are: America/Antigua, America/Cayman,
3358    Pacific/Midway, and Pacific/Saipan.
3359
3360  Changes affecting time zone abbreviations
3361
3362    Correct the 1992-2010 DST abbreviation in Volgograd from "MSK" to "MSD".
3363    (Thanks to Hank W.)
3364
3365  Changes affecting code
3366
3367    Fix integer overflow bug in reference 'mktime' implementation.
3368    (Problem reported by Jörg Richter.)
3369
3370    Allow -Dtime_tz=time_t compilations, and allow -Dtime_tz=... libraries
3371    to be used in the same executable as standard-library time_t functions.
3372    (Problems reported by Bradley White.)
3373
3374  Changes affecting commentary
3375
3376    Cite the recent Mexican decree changing Quintana Roo's time zone.
3377    (Thanks to Carlos Raúl Perasso.)
3378
3379    Likewise for the recent Chilean decree.  (Thanks to Eduardo Romero Urra.)
3380
3381    Update info about Mars time.
3382
3383
3384Release 2015a - 2015-01-29 22:35:20 -0800
3385
3386  Changes affecting future timestamps
3387
3388    The Mexican state of Quintana Roo, represented by America/Cancun,
3389    will shift from Central Time with DST to Eastern Time without DST
3390    on 2015-02-01 at 02:00.  (Thanks to Steffen Thorsen and Gwillim Law.)
3391
3392    Chile will not change clocks in April or thereafter; its new standard time
3393    will be its old daylight saving time.  This affects America/Santiago,
3394    Pacific/Easter, and Antarctica/Palmer.  (Thanks to Juan Correa.)
3395
3396    New leap second 2015-06-30 23:59:60 UTC as per IERS Bulletin C 49.
3397    (Thanks to Tim Parenti.)
3398
3399  Changes affecting past timestamps
3400
3401    Iceland observed DST in 1919 and 1921, and its 1939 fallback
3402    transition was Oct. 29, not Nov. 29.  Remove incorrect data from
3403    Shanks about time in Iceland between 1837 and 1908.
3404
3405    Some more zones have been turned into links, when they differed
3406    from existing zones only for older timestamps.  As usual,
3407    these changes affect UT offsets in pre-1970 timestamps only.
3408    Their old contents have been moved to the 'backzone' file.
3409    The affected zones are: Asia/Aden, Asia/Bahrain, Asia/Kuwait,
3410    and Asia/Muscat.
3411
3412  Changes affecting code
3413
3414    tzalloc now scrubs time zone abbreviations compatibly with the way
3415    that tzset always has, by replacing invalid bytes with '_' and by
3416    shortening too-long abbreviations.
3417
3418    tzselect ports to POSIX awk implementations, no longer mishandles
3419    POSIX TZ settings when GNU awk is used, and reports POSIX TZ
3420    settings to the user.  (Thanks to Stefan Kuhn.)
3421
3422  Changes affecting build procedure
3423
3424    'make check' now checks for links to links in the data.
3425    One such link (for Africa/Asmera) has been fixed.
3426    (Thanks to Stephen Colebourne for pointing out the problem.)
3427
3428  Changes affecting commentary
3429
3430    The leapseconds file commentary now mentions the expiration date.
3431    (Problem reported by Martin Burnicki.)
3432
3433    Update Mexican Library of Congress URL.
3434
3435
3436Release 2014j - 2014-11-10 17:37:11 -0800
3437
3438  Changes affecting current and future timestamps
3439
3440    Turks & Caicos' switch from US eastern time to UT -04 year-round
3441    did not occur on 2014-11-02 at 02:00.  It's currently scheduled
3442    for 2015-11-01 at 02:00.  (Thanks to Chris Walton.)
3443
3444  Changes affecting past timestamps
3445
3446    Many pre-1989 timestamps have been corrected for Asia/Seoul and
3447    Asia/Pyongyang, based on sources for the Korean-language Wikipedia
3448    entry for time in Korea.  (Thanks to Sanghyuk Jung.)  Also, no
3449    longer guess that Pyongyang mimicked Seoul time after World War II,
3450    as this is politically implausible.
3451
3452    Some more zones have been turned into links, when they differed
3453    from existing zones only for older timestamps.  As usual,
3454    these changes affect UT offsets in pre-1970 timestamps only.
3455    Their old contents have been moved to the 'backzone' file.
3456    The affected zones are: Africa/Addis_Ababa, Africa/Asmara,
3457    Africa/Dar_es_Salaam, Africa/Djibouti, Africa/Kampala,
3458    Africa/Mogadishu, Indian/Antananarivo, Indian/Comoro, and
3459    Indian/Mayotte.
3460
3461  Changes affecting commentary
3462
3463    The commentary is less enthusiastic about Shanks as a source,
3464    and is more careful to distinguish UT from UTC.
3465
3466
3467Release 2014i - 2014-10-21 22:04:57 -0700
3468
3469  Changes affecting future timestamps
3470
3471    Pacific/Fiji will observe DST from 2014-11-02 02:00 to 2015-01-18 03:00.
3472    (Thanks to Ken Rylander for the heads-up.)  Guess that future
3473    years will use a similar pattern.
3474
3475    A new Zone Pacific/Bougainville, for the part of Papua New Guinea
3476    that plans to switch from UT +10 to +11 on 2014-12-28 at 02:00.
3477    (Thanks to Kiley Walbom for the heads-up.)
3478
3479  Changes affecting time zone abbreviations
3480
3481    Since Belarus is not changing its clocks even though Moscow is,
3482    the time zone abbreviation in Europe/Minsk is changing from FET
3483    to its more traditional value MSK on 2014-10-26 at 01:00.
3484    (Thanks to Alexander Bokovoy for the heads-up about Belarus.)
3485
3486    The new abbreviation IDT stands for the pre-1976 use of UT +08 in
3487    Indochina, to distinguish it better from ICT (+07).
3488
3489  Changes affecting past timestamps
3490
3491    Many timestamps have been corrected for Asia/Ho_Chi_Minh before 1976
3492    (thanks to Trần Ngọc Quân for an indirect pointer to Trần Tiến Bình's
3493    authoritative book).  Asia/Ho_Chi_Minh has been added to
3494    zone1970.tab, to give tzselect users in Vietnam two choices,
3495    since north and south Vietnam disagreed after our 1970 cutoff.
3496
3497    Asia/Phnom_Penh and Asia/Vientiane have been turned into links, as
3498    they differed from existing zones only for older timestamps.  As
3499    usual, these changes affect pre-1970 timestamps only.  Their old
3500    contents have been moved to the 'backzone' file.
3501
3502  Changes affecting code
3503
3504    The time-related library functions now set errno on failure, and
3505    some crashes in the new tzalloc-related library functions have
3506    been fixed.  (Thanks to Christos Zoulas for reporting most of
3507    these problems and for suggesting fixes.)
3508
3509    If USG_COMPAT is defined and the requested timestamp is standard time,
3510    the tz library's localtime and mktime functions now set the extern
3511    variable timezone to a value appropriate for that timestamp; and
3512    similarly for ALTZONE, daylight saving time, and the altzone variable.
3513    This change is a companion to the tzname change in 2014h, and is
3514    designed to make timezone and altzone more compatible with tzname.
3515
3516    The tz library's functions now set errno to EOVERFLOW if they fail
3517    because the result cannot be represented.  ctime and ctime_r now
3518    return NULL and set errno when a timestamp is out of range, rather
3519    than having undefined behavior.
3520
3521    Some bugs associated with the new 2014g functions have been fixed.
3522    This includes a bug that largely incapacitated the new functions
3523    time2posix_z and posix2time_z.  (Thanks to Christos Zoulas.)
3524    It also includes some uses of uninitialized variables after tzalloc.
3525    The new code uses the standard type 'ssize_t', which the Makefile
3526    now gives porting advice about.
3527
3528  Changes affecting commentary
3529
3530    Updated URLs for NRC Canada (thanks to Matt Johnson and Brian Inglis).
3531
3532
3533Release 2014h - 2014-09-25 18:59:03 -0700
3534
3535  Changes affecting past timestamps
3536
3537    America/Jamaica's 1974 spring-forward transition was Jan. 6, not Apr. 28.
3538
3539    Shanks says Asia/Novokuznetsk switched from LMT (not "NMT") on 1924-05-01,
3540    not 1920-01-06.  The old entry was based on a misinterpretation of Shanks.
3541
3542    Some more zones have been turned into links, when they differed
3543    from existing zones only for older timestamps.  As usual,
3544    these changes affect UT offsets in pre-1970 timestamps only.
3545    Their old contents have been moved to the 'backzone' file.
3546    The affected zones are: Africa/Blantyre, Africa/Bujumbura,
3547    Africa/Gaborone, Africa/Harare, Africa/Kigali, Africa/Lubumbashi,
3548    Africa/Lusaka, Africa/Maseru, and Africa/Mbabane.
3549
3550  Changes affecting code
3551
3552    zdump -V and -v now output gmtoff= values on all platforms,
3553    not merely on platforms defining TM_GMTOFF.
3554
3555    The tz library's localtime and mktime functions now set tzname to a value
3556    appropriate for the requested timestamp, and zdump now uses this
3557    on platforms not defining TM_ZONE, fixing a 2014g regression.
3558    (Thanks to Tim Parenti for reporting the problem.)
3559
3560    The tz library no longer sets tzname if localtime or mktime fails.
3561
3562    zdump -c no longer mishandles transitions near year boundaries.
3563    (Thanks to Tim Parenti for reporting the problem.)
3564
3565    An access to uninitialized data has been fixed.
3566    (Thanks to Jörg Richter for reporting the problem.)
3567
3568    When THREAD_SAFE is defined, the code ports to the C11 memory model.
3569    A memory leak has been fixed if ALL_STATE and THREAD_SAFE are defined
3570    and two threads race to initialize data used by gmtime-like functions.
3571    (Thanks to Andy Heninger for reporting the problems.)
3572
3573  Changes affecting build procedure
3574
3575    'make check' now checks better for properly sorted data.
3576
3577  Changes affecting documentation and commentary
3578
3579    zdump's gmtoff=N output is now documented, and its isdst=D output
3580    is now documented to possibly output D values other than 0 or 1.
3581
3582    zdump -c's treatment of years is now documented to use the
3583    Gregorian calendar and Universal Time without leap seconds,
3584    and its behavior at cutoff boundaries is now documented better.
3585    (Thanks to Arthur David Olson and Tim Parenti for reporting the problems.)
3586
3587    Programs are now documented to use the proleptic Gregorian calendar.
3588    (Thanks to Alan Barrett for the suggestion.)
3589
3590    Fractional-second GMT offsets have been documented for civil time
3591    in 19th-century Chennai, Jakarta, and New York.
3592
3593
3594Release 2014g - 2014-08-28 12:31:23 -0700
3595
3596  Changes affecting future timestamps
3597
3598    Turks & Caicos is switching from US eastern time to UT -04
3599    year-round, modeled as a switch on 2014-11-02 at 02:00.
3600    [As noted in 2014j, this switch was later delayed.]
3601
3602  Changes affecting past timestamps
3603
3604    Time in Russia or the USSR before 1926 or so has been corrected by
3605    a few seconds in the following zones: Asia/Irkutsk,
3606    Asia/Krasnoyarsk, Asia/Omsk, Asia/Samarkand, Asia/Tbilisi,
3607    Asia/Vladivostok, Asia/Yakutsk, Europe/Riga, Europe/Samara.  For
3608    Asia/Yekaterinburg the correction is a few minutes.  (Thanks to
3609    Vladimir Karpinsky.)
3610
3611    The Portuguese decree of 1911-05-26 took effect on 1912-01-01.
3612    This affects 1911 timestamps in Africa/Bissau, Africa/Luanda,
3613    Atlantic/Azores, and Atlantic/Madeira.  Also, Lisbon's pre-1912
3614    GMT offset was -0:36:45 (rounded from -0:36:44.68), not -0:36:32.
3615    (Thanks to Stephen Colebourne for pointing to the decree.)
3616
3617    Asia/Dhaka ended DST on 2009-12-31 at 24:00, not 23:59.
3618
3619    A new file 'backzone' contains data which may appeal to
3620    connoisseurs of old timestamps, although it is out of scope for
3621    the tz database, is often poorly sourced, and contains some data
3622    that is known to be incorrect.  The new file is not recommended
3623    for ordinary use and its entries are not installed by default.
3624    (Thanks to Lester Caine for the high-quality Jersey, Guernsey, and
3625    Isle of Man entries.)
3626
3627    Some more zones have been turned into links, when they differed
3628    from existing zones only for older timestamps.  As usual,
3629    these changes affect UT offsets in pre-1970 timestamps only.
3630    Their old contents have been moved to the 'backzone' file.
3631    The affected zones are: Africa/Bangui, Africa/Brazzaville,
3632    Africa/Douala, Africa/Kinshasa, Africa/Libreville, Africa/Luanda,
3633    Africa/Malabo, Africa/Niamey, and Africa/Porto-Novo.
3634
3635  Changes affecting code
3636
3637    Unless NETBSD_INSPIRED is defined to 0, the tz library now
3638    supplies functions for creating and using objects that represent
3639    timezones. The new functions are tzalloc, tzfree, localtime_rz,
3640    mktime_z, and (if STD_INSPIRED is also defined) posix2time_z and
3641    time2posix_z.  They are intended for performance: for example,
3642    localtime_rz (unlike localtime_r) is trivially thread-safe without
3643    locking.  (Thanks to Christos Zoulas for proposing NetBSD-inspired
3644    functions, and to Alan Barrett and Jonathan Lennox for helping to
3645    debug the change.)
3646
3647    zdump now builds with the tz library unless USE_LTZ is defined to 0,
3648    This lets zdump use tz features even if the system library lacks them.
3649    To build zdump with the system library, use 'make CFLAGS=-DUSE_LTZ=0
3650    TZDOBJS=zdump.o CHECK_TIME_T_ALTERNATIVES='.
3651
3652    zdump now uses localtime_rz if available, as it's significantly faster,
3653    and it can help zdump better diagnose invalid timezone names.
3654    Define HAVE_LOCALTIME_RZ to 0 to suppress this.  HAVE_LOCALTIME_RZ
3655    defaults to 1 if NETBSD_INSPIRED && USE_LTZ.  When localtime_rz is
3656    not available, zdump now uses localtime_r and tzset if available,
3657    as this is a bit cleaner and faster than plain localtime.  Compile
3658    with -DHAVE_LOCALTIME_R=0 and/or -DHAVE_TZSET=0 if your system
3659    lacks these two functions.
3660
3661    If THREAD_SAFE is defined to 1, the tz library is now thread-safe.
3662    Although not needed for tz's own applications, which are single-threaded,
3663    this supports POSIX better if the tz library is used in multithreaded apps.
3664
3665    Some crashes have been fixed when zdump or the tz library is given
3666    invalid or outlandish input.
3667
3668    The tz library no longer mishandles leap seconds on platforms with
3669    unsigned time_t in timezones that lack ordinary transitions after 1970.
3670
3671    The tz code now attempts to infer TM_GMTOFF and TM_ZONE if not
3672    already defined, to make it easier to configure on common platforms.
3673    Define NO_TM_GMTOFF and NO_TM_ZONE to suppress this.
3674
3675    Unless the new macro UNINIT_TRAP is defined to 1, the tz code now
3676    assumes that reading uninitialized memory yields garbage values
3677    but does not cause other problems such as traps.
3678
3679    If TM_GMTOFF is defined and UNINIT_TRAP is 0, mktime is now
3680    more likely to guess right for ambiguous timestamps near
3681    transitions where tm_isdst does not change.
3682
3683    If HAVE_STRFTIME_L is defined to 1, the tz library now defines
3684    strftime_l for compatibility with recent versions of POSIX.
3685    Only the C locale is supported, though.  HAVE_STRFTIME_L defaults
3686    to 1 on recent POSIX versions, and to 0 otherwise.
3687
3688    tzselect -c now uses a hybrid distance measure that works better
3689    in Africa.  (Thanks to Alan Barrett for noting the problem.)
3690
3691    The C source code now ports to NetBSD when GCC_DEBUG_FLAGS is used,
3692    or when time_tz is defined.
3693
3694    When HAVE_UTMPX_H is set the 'date' command now builds on systems
3695    whose <utmpx.h> file does not define WTMPX_FILE, and when setting
3696    the date it updates the wtmpx file if _PATH_WTMPX is defined.
3697    This affects GNU/Linux and similar systems.
3698
3699    For easier maintenance later, some C code has been simplified,
3700    some lint has been removed, and the code has been tweaked so that
3701    plain 'make' is more likely to work.
3702
3703    The C type 'bool' is now used for boolean values, instead of 'int'.
3704
3705    The long-obsolete LOCALE_HOME code has been removed.
3706
3707    The long-obsolete 'gtime' function has been removed.
3708
3709  Changes affecting build procedure
3710
3711    'zdump' no longer links in ialloc.o, as it's not needed.
3712
3713    'make check_time_t_alternatives' no longer assumes GNU diff.
3714
3715  Changes affecting distribution tarballs
3716
3717    The files checktab.awk and zoneinfo2tdf.pl are now distributed in
3718    the tzdata tarball instead of the tzcode tarball, since they help
3719    maintain the data.  The NEWS and Theory files are now also
3720    distributed in the tzdata tarball, as they're relevant for data.
3721    (Thanks to Alan Barrett for pointing this out.)  Also, the
3722    leapseconds.awk file is no longer distributed in the tzcode
3723    tarball, since it belongs in the tzdata tarball (where 2014f
3724    inadvertently also distributed it).
3725
3726  Changes affecting documentation and commentary
3727
3728    A new file CONTRIBUTING is distributed.  (Thanks to Tim Parenti for
3729    suggesting a CONTRIBUTING file, and to Tony Finch and Walter Harms
3730    for debugging it.)
3731
3732    The man pages have been updated to use function prototypes,
3733    to document thread-safe variants like localtime_r, and to document
3734    the NetBSD-inspired functions tzalloc, tzfree, localtime_rz, and
3735    mktime_z.
3736
3737    The fields in Link lines have been renamed to be more descriptive
3738    and more like the parameters of 'ln'.  LINK-FROM has become TARGET,
3739    and LINK-TO has become LINK-NAME.
3740
3741    tz-link.htm mentions the IETF's tzdist working group; Windows
3742    Runtime etc. (thanks to Matt Johnson); and HP-UX's tztab.
3743
3744    Some broken URLs have been fixed in the commentary.  (Thanks to
3745    Lester Caine.)
3746
3747    Commentary about Philippines DST has been updated, and commentary
3748    on pre-1970 time in India has been added.
3749
3750
3751Release 2014f - 2014-08-05 17:42:36 -0700
3752
3753  Changes affecting future timestamps
3754
3755    Russia will subtract an hour from most of its time zones on 2014-10-26
3756    at 02:00 local time.  (Thanks to Alexander Krivenyshev.)
3757    There are a few exceptions: Magadan Oblast (Asia/Magadan) and Zabaykalsky
3758    Krai are subtracting two hours; conversely, Chukotka Autonomous Okrug
3759    (Asia/Anadyr), Kamchatka Krai (Asia/Kamchatka), Kemerovo Oblast
3760    (Asia/Novokuznetsk), and the Samara Oblast and the Udmurt Republic
3761    (Europe/Samara) are not changing their clocks.  The changed zones are
3762    Europe/Kaliningrad, Europe/Moscow, Europe/Simferopol, Europe/Volgograd,
3763    Asia/Yekaterinburg, Asia/Omsk, Asia/Novosibirsk, Asia/Krasnoyarsk,
3764    Asia/Irkutsk, Asia/Yakutsk, Asia/Vladivostok, Asia/Khandyga,
3765    Asia/Sakhalin, and Asia/Ust-Nera; Asia/Magadan will have two hours
3766    subtracted; and Asia/Novokuznetsk's time zone abbreviation is affected,
3767    but not its UTC offset.  Two zones are added: Asia/Chita (split
3768    from Asia/Yakutsk, and also with two hours subtracted) and
3769    Asia/Srednekolymsk (split from Asia/Magadan, but with only one hour
3770    subtracted).  (Thanks to Tim Parenti for much of the above.)
3771
3772  Changes affecting time zone abbreviations
3773
3774    Australian eastern time zone abbreviations are now AEST/AEDT not EST,
3775    and similarly for the other Australian zones.  That is, for eastern
3776    standard and daylight saving time the abbreviations are AEST and AEDT
3777    instead of the former EST for both; similarly, ACST/ACDT, ACWST/ACWDT,
3778    and AWST/AWDT are now used instead of the former CST, CWST, and WST.
3779    This change does not affect UT offsets, only time zone abbreviations.
3780    (Thanks to Rich Tibbett and many others.)
3781
3782    Asia/Novokuznetsk shifts from NOVT to KRAT (remaining on UT +07)
3783    effective 2014-10-26 at 02:00 local time.
3784
3785    The time zone abbreviation for Xinjiang Time (observed in Ürümqi)
3786    has been changed from URUT to XJT.  (Thanks to Luther Ma.)
3787
3788    Prefer MSK/MSD for Moscow time in Russia, even in other cities.
3789    Similarly, prefer EET/EEST for eastern European time in Russia.
3790
3791    Change time zone abbreviations in (western) Samoa to use "ST" and
3792    "DT" suffixes, as this is more likely to match common practice.
3793    Prefix "W" to (western) Samoa time when its standard-time offset
3794    disagrees with that of American Samoa.
3795
3796    America/Metlakatla now uses PST, not MeST, to abbreviate its time zone.
3797
3798    Time zone abbreviations have been updated for Japan's two time
3799    zones used 1896-1937.  JWST now stands for Western Standard
3800    Time, and JCST for Central Standard Time (formerly this was CJT).
3801    These abbreviations are now used for time in Korea, Taiwan,
3802    and Sakhalin while controlled by Japan.
3803
3804  Changes affecting past timestamps
3805
3806    China's five zones have been simplified to two, since the post-1970
3807    differences in the other three seem to have been imaginary.  The
3808    zones Asia/Harbin, Asia/Chongqing, and Asia/Kashgar have been
3809    removed; backwards-compatibility links still work, albeit with
3810    different behaviors for timestamps before May 1980.  Asia/Urumqi's
3811    1980 transition to UT +08 has been removed, so that it is now at
3812    +06 and not +08.  (Thanks to Luther Ma and to Alois Treindl;
3813    Treindl sent helpful translations of two papers by Guo Qingsheng.)
3814
3815    Some zones have been turned into links, when they differed from existing
3816    zones only for older UT offsets where data entries were likely invented.
3817    These changes affect UT offsets in pre-1970 timestamps only.  This is
3818    similar to the change in release 2013e, except this time for western
3819    Africa.  The affected zones are: Africa/Bamako, Africa/Banjul,
3820    Africa/Conakry, Africa/Dakar, Africa/Freetown, Africa/Lome,
3821    Africa/Nouakchott, Africa/Ouagadougou, Africa/Sao_Tome, and
3822    Atlantic/St_Helena.  This also affects the backwards-compatibility
3823    link Africa/Timbuktu.  (Thanks to Alan Barrett, Stephen Colebourne,
3824    Tim Parenti, and David Patte for reporting problems in earlier
3825    versions of this change.)
3826
3827    Asia/Shanghai's pre-standard-time UT offset has been changed from
3828    8:05:57 to 8:05:43, the location of Xujiahui Observatory.  Its
3829    transition to standard time has been changed from 1928 to 1901.
3830
3831    Asia/Taipei switched to JWST on 1896-01-01, then to JST on 1937-10-01,
3832    then to CST on 1945-09-21 at 01:00, and did not observe DST in 1945.
3833    In 1946 it observed DST from 05-15 through 09-30; in 1947
3834    from 04-15 through 10-31; and in 1979 from 07-01 through 09-30.
3835    (Thanks to Yu-Cheng Chuang.)
3836
3837    Asia/Riyadh's transition to standard time is now 1947-03-14, not 1950.
3838
3839    Europe/Helsinki's 1942 fall-back transition was 10-04 at 01:00, not
3840    10-03 at 00:00.  (Thanks to Konstantin Hyppönen.)
3841
3842    Pacific/Pago_Pago has been changed from UT -11:30 to -11 for the
3843    period from 1911 to 1950.
3844
3845    Pacific/Chatham has been changed to New Zealand standard time plus
3846    45 minutes for the period before 1957, reflecting a 1956 remark in
3847    the New Zealand parliament.
3848
3849    Europe/Budapest has several pre-1946 corrections: in 1918 the transition
3850    out of DST was on 09-16, not 09-29; in 1919 it was on 11-24, not 09-15; in
3851    1945 it was on 11-01, not 11-03; in 1941 the transition to DST was 04-08
3852    not 04-06 at 02:00; and there was no DST in 1920.
3853
3854    Africa/Accra is now assumed to have observed DST from 1920 through 1935.
3855
3856    Time in Russia before 1927 or so has been corrected by a few seconds in
3857    the following zones: Europe/Moscow, Asia/Irkutsk, Asia/Tbilisi,
3858    Asia/Tashkent, Asia/Vladivostok, Asia/Yekaterinburg, Europe/Helsinki, and
3859    Europe/Riga.  Also, Moscow's location has been changed to its Kilometer 0
3860    point.  (Thanks to Vladimir Karpinsky for the Moscow changes.)
3861
3862  Changes affecting data format
3863
3864    A new file 'zone1970.tab' supersedes 'zone.tab' in the installed data.
3865    The new file's extended format allows multiple country codes per zone.
3866    The older file is still installed but is deprecated; its format is
3867    not changing and it will still be distributed for a while, but new
3868    applications should use the new file.
3869
3870    The new file format simplifies maintenance of obscure locations.
3871    To test this, it adds coverage for the Crozet Islands and the
3872    Scattered Islands.  (Thanks to Tobias Conradi and Antoine Leca.)
3873
3874    The file 'iso3166.tab' is planned to switch from ASCII to UTF-8.
3875    It is still ASCII now, but commentary about the switch has been added.
3876    The new file 'zone1970.tab' already uses UTF-8.
3877
3878  Changes affecting code
3879
3880    'localtime', 'mktime', etc. now use much less stack space if ALL_STATE
3881    is defined.  (Thanks to Elliott Hughes for reporting the problem.)
3882
3883    'zic' no longer mishandles input when ignoring case in locales that
3884    are not compatible with English, e.g., unibyte Turkish locales when
3885    compiled with HAVE_GETTEXT.
3886
3887    Error diagnostics of 'zic' and 'yearistype' have been reworded so that
3888    they no longer use ASCII '-' as if it were a dash.
3889
3890    'zic' now rejects output file names that contain '.' or '..' components.
3891    (Thanks to Tim Parenti for reporting the problem.)
3892
3893    'zic -v' now warns about output file names that do not follow
3894    POSIX rules, or that contain a digit or '.'.  (Thanks to Arthur
3895    David Olson for starting the ball rolling on this.)
3896
3897    Some lint has been removed when using GCC_DEBUG_FLAGS with GCC 4.9.0.
3898
3899  Changes affecting build procedure
3900
3901    'zic' no longer links in localtime.o and asctime.o, as they're not needed.
3902    (Thanks to John Cochran.)
3903
3904  Changes affecting documentation and commentary
3905
3906    The 'Theory' file documents legacy names, the longstanding
3907    exceptions to the POSIX-inspired file name rules.
3908
3909    The 'zic' documentation clarifies the role of time types when
3910    interpreting dates.  (Thanks to Arthur David Olson.)
3911
3912    Documentation and commentary now prefer UTF-8 to US-ASCII,
3913    allowing the use of proper accents in foreign words and names.
3914    Code and data have not changed because of this.  (Thanks to
3915    Garrett Wollman, Ian Abbott, and Guy Harris for helping to debug
3916    this.)
3917
3918    Non-HTML documentation and commentary now use plain-text URLs instead of
3919    HTML insertions, and are more consistent about bracketing URLs when they
3920    are not already surrounded by white space.  (Thanks to suggestions by
3921    Steffen Nurpmeso.)
3922
3923    There is new commentary about Xujiahui Observatory, the five time-zone
3924    project in China from 1918 to 1949, timekeeping in Japanese-occupied
3925    Shanghai, and Tibet Time in the 1950s.  The sharp-eyed can spot the
3926    warlord Jin Shuren in the data.
3927
3928    Commentary about the coverage of each Russian zone has been standardized.
3929    (Thanks to Tim Parenti.)
3930
3931    There is new commentary about contemporary timekeeping in Ethiopia.
3932
3933    Obsolete comments about a 2007 proposal for DST in Kuwait has been removed.
3934
3935    There is new commentary about time in Poland in 1919.
3936
3937    Proper credit has been given to DST inventor George Vernon Hudson.
3938
3939    Commentary about time in Metlakatla, AK and Resolute, NU has been
3940    improved, with a new source for the former.
3941
3942    In zone.tab, Pacific/Easter no longer mentions Salas y Gómez, as it
3943    is uninhabited.
3944
3945    Commentary about permanent Antarctic bases has been updated.
3946
3947    Several typos have been corrected.  (Thanks to Tim Parenti for
3948    contributing some of these fixes.)
3949
3950    tz-link.htm now mentions the JavaScript libraries Moment Timezone,
3951    TimezoneJS.Date, Walltime-js, and Timezone.  (Thanks to a heads-up
3952    from Matt Johnson.)  Also, it mentions the Go 'latlong' package.
3953    (Thanks to a heads-up from Dirkjan Ochtman.)
3954
3955    The files usno1988, usno1989, usno1989a, usno1995, usno1997, and usno1998
3956    have been removed.  These obsolescent US Naval Observatory entries were no
3957    longer helpful for maintenance.  (Thanks to Tim Parenti for the suggestion.)
3958
3959
3960Release 2014e - 2014-06-12 21:53:52 -0700
3961
3962  Changes affecting near-future timestamps
3963
3964    Egypt's 2014 Ramadan-based transitions are June 26 and July 31 at 24:00.
3965    (Thanks to Imed Chihi.)  Guess that from 2015 on Egypt will temporarily
3966    switch to standard time at 24:00 the last Thursday before Ramadan, and
3967    back to DST at 00:00 the first Friday after Ramadan.
3968
3969    Similarly, Morocco's are June 28 at 03:00 and August 2 at 02:00.  (Thanks
3970    to Milamber Space Network.)  Guess that from 2015 on Morocco will
3971    temporarily switch to standard time at 03:00 the last Saturday before
3972    Ramadan, and back to DST at 02:00 the first Saturday after Ramadan.
3973
3974  Changes affecting past timestamps
3975
3976    The abbreviation "MSM" (Moscow Midsummer Time) is now used instead of
3977    "MSD" for Moscow's double daylight time in summer 1921.  Also, a typo
3978    "VLASST" has been repaired to be "VLAST" for Vladivostok summer time
3979    in 1991.  (Thanks to Hank W. for reporting the problems.)
3980
3981  Changes affecting commentary
3982
3983    tz-link.htm now cites RFC 7265 for jCal, mentions PTP and the
3984    draft CalDAV extension, updates URLs for TSP, TZInfo, IATA, and
3985    removes stale pointers to World Time Explorer and WORLDTIME.
3986
3987
3988Release 2014d - 2014-05-27 21:34:40 -0700
3989
3990  Changes affecting code
3991
3992    zic no longer generates files containing timestamps before the Big Bang.
3993    This works around GNOME glib bug 878
3994    <https://gitlab.gnome.org/GNOME/glib/issues/878>
3995    (Thanks to Leonardo Chiquitto for reporting the bug, and to
3996    Arthur David Olson and James Cloos for suggesting improvements to the fix.)
3997
3998  Changes affecting documentation
3999
4000    tz-link.htm now mentions GNOME.
4001
4002
4003Release 2014c - 2014-05-13 07:44:13 -0700
4004
4005  Changes affecting near-future timestamps
4006
4007    Egypt observes DST starting 2014-05-15 at 24:00.
4008    (Thanks to Ahmad El-Dardiry and Gunther Vermier.)
4009    Details have not been announced, except that DST will not be observed
4010    during Ramadan.  Guess that DST will stop during the same Ramadan dates as
4011    Morocco, and that Egypt's future spring and fall transitions will be the
4012    same as 2010 when it last observed DST, namely April's last Friday at
4013    00:00 to September's last Thursday at 23:00 standard time.  Also, guess
4014    that Ramadan transitions will be at 00:00 standard time.
4015
4016  Changes affecting code
4017
4018    zic now generates transitions for minimum time values, eliminating guesswork
4019    when handling low-valued timestamps.  (Thanks to Arthur David Olson.)
4020
4021    Port to Cygwin sans glibc.  (Thanks to Arthur David Olson.)
4022
4023  Changes affecting commentary and documentation
4024
4025    Remove now-confusing comment about Jordan.  (Thanks to Oleksii Nochovnyi.)
4026
4027
4028Release 2014b - 2014-03-24 21:28:50 -0700
4029
4030  Changes affecting near-future timestamps
4031
4032    Crimea switches to Moscow time on 2014-03-30 at 02:00 local time.
4033    (Thanks to Alexander Krivenyshev.)  Move its zone.tab entry from UA to RU.
4034
4035    New entry for Troll station, Antarctica.  (Thanks to Paul-Inge Flakstad and
4036    Bengt-Inge Larsson.)  This is currently an approximation; a better version
4037    will require the zic and localtime fixes mentioned below, and the plan is
4038    to wait for a while until at least the zic fixes propagate.
4039
4040  Changes affecting code
4041
4042    'zic' and 'localtime' no longer reject locations needing four transitions
4043    per year for the foreseeable future.  (Thanks to Andrew Main (Zefram).)
4044    Also, 'zic' avoids some unlikely failures due to integer overflow.
4045
4046  Changes affecting build procedure
4047
4048    'make check' now detects Rule lines defined but never used.
4049    The NZAQ rules, an instance of this problem, have been removed.
4050
4051  Changes affecting commentary and documentation
4052
4053    Fix Tuesday/Thursday typo in description of time in Israel.
4054    (Thanks to Bert Katz via Pavel Kharitonov and Mike Frysinger.)
4055
4056    Microsoft Windows 8.1 doesn't support tz database names.  (Thanks
4057    to Donald MacQueen.)  Instead, the Microsoft Windows Store app
4058    library supports them.
4059
4060    Add comments about Johnston Island time in the 1960s.
4061    (Thanks to Lyle McElhaney.)
4062
4063    Morocco's 2014 DST start will be as predicted.
4064    (Thanks to Sebastien Willemijns.)
4065
4066
4067Release 2014a - 2014-03-07 23:30:29 -0800
4068
4069  Changes affecting near-future timestamps
4070
4071    Turkey begins DST on 2014-03-31, not 03-30.  (Thanks to Faruk Pasin for
4072    the heads-up, and to Tim Parenti for simplifying the update.)
4073
4074  Changes affecting past timestamps
4075
4076    Fiji ended DST on 2014-01-19 at 02:00, not the previously scheduled 03:00.
4077    (Thanks to Steffen Thorsen.)
4078
4079    Ukraine switched from Moscow to Eastern European time on 1990-07-01
4080    (not 1992-01-01), and observed DST during the entire next winter.
4081    (Thanks to Vladimir in Moscow via Alois Treindl.)
4082
4083    In 1988 Israel observed DST from 04-10 to 09-04, not 04-09 to 09-03.
4084    (Thanks to Avigdor Finkelstein.)
4085
4086  Changes affecting code
4087
4088    A uninitialized-storage bug in 'localtime' has been fixed.
4089    (Thanks to Logan Chien.)
4090
4091  Changes affecting the build procedure
4092
4093    The settings for 'make check_web' now default to Ubuntu 13.10.
4094
4095  Changes affecting commentary and documentation
4096
4097    The boundary of the US Pacific time zone is given more accurately.
4098    (Thanks to Alan Mintz.)
4099
4100    Chile's 2014 DST will be as predicted.  (Thanks to José Miguel Garrido.)
4101
4102    Paraguay's 2014 DST will be as predicted.  (Thanks to Carlos Raúl Perasso.)
4103
4104    Better descriptions of countries with same time zone history as
4105    Trinidad and Tobago since 1970.  (Thanks to Alan Barrett for suggestion.)
4106
4107    Several changes affect tz-link.htm, the main web page.
4108
4109      Mention Time.is (thanks to Even Scharning) and WX-now (thanks to
4110      David Braverman).
4111
4112      Mention xCal (Internet RFC 6321) and jCal.
4113
4114      Microsoft has some support for tz database names.
4115
4116      CLDR data formats include both XML and JSON.
4117
4118      Mention Maggiolo's map of solar vs standard time.
4119      (Thanks to Arthur David Olson.)
4120
4121      Mention TZ4Net.  (Thanks to Matt Johnson.)
4122
4123      Mention the timezone-olson Haskell package.
4124
4125      Mention zeitverschiebung.net.  (Thanks to Martin Jäger.)
4126
4127      Remove moribund links to daylight-savings-time.info and to
4128      Simple Timer + Clocks.
4129
4130      Update two links.  (Thanks to Oscar van Vlijmen.)
4131
4132      Fix some formatting glitches, e.g., remove random newlines from
4133      abbr elements' title attributes.
4134
4135
4136Release 2013i - 2013-12-17 07:25:23 -0800
4137
4138  Changes affecting near-future timestamps:
4139
4140    Jordan switches back to standard time at 00:00 on December 20, 2013.
4141    The 2006-2011 transition schedule is planned to resume in 2014.
4142    (Thanks to Steffen Thorsen.)
4143
4144  Changes affecting past timestamps:
4145
4146    In 2004, Cuba began DST on March 28, not April 4.
4147    (Thanks to Steffen Thorsen.)
4148
4149  Changes affecting code
4150
4151    The compile-time flag NOSOLAR has been removed, as nowadays the
4152    benefit of slightly shrinking runtime table size is outweighed by the
4153    cost of disallowing potential future updates that exceed old limits.
4154
4155  Changes affecting documentation and commentary
4156
4157    The files solar87, solar88, and solar89 are no longer distributed.
4158    They were a negative experiment - that is, a demonstration that
4159    tz data can represent solar time only with some difficulty and error.
4160    Their presence in the distribution caused confusion, as Riyadh
4161    civil time was generally not solar time in those years.
4162
4163    tz-link.htm now mentions Noda Time.  (Thanks to Matt Johnson.)
4164
4165
4166Release 2013h - 2013-10-25 15:32:32 -0700
4167
4168  Changes affecting current and future timestamps:
4169
4170    Libya has switched its UT offset back to +02 without DST, instead
4171    of +01 with DST.  (Thanks to Even Scharning.)
4172
4173    Western Sahara (Africa/El_Aaiun) uses Morocco's DST rules.
4174    (Thanks to Gwillim Law.)
4175
4176  Changes affecting future timestamps:
4177
4178    Acre and (we guess) western Amazonas will switch from UT -04 to -05
4179    on 2013-11-10.  This affects America/Rio_Branco and America/Eirunepe.
4180    (Thanks to Steffen Thorsen.)
4181
4182    Add entries for DST transitions in Morocco in the year 2038.
4183    This avoids some year-2038 glitches introduced in 2013g.
4184    (Thanks to Yoshito Umaoka for reporting the problem.)
4185
4186  Changes affecting API
4187
4188    The 'tzselect' command no longer requires the 'select' command,
4189    and should now work with /bin/sh on more platforms.  It also works
4190    around a bug in BusyBox awk before version 1.21.0.  (Thanks to
4191    Patrick 'P. J.' McDermott and Alan Barrett.)
4192
4193  Changes affecting code
4194
4195    Fix localtime overflow bugs with 32-bit unsigned time_t.
4196
4197    zdump no longer assumes sscanf returns maximal values on overflow.
4198
4199  Changes affecting the build procedure
4200
4201    The builder can specify which programs to use, if any, instead of
4202    'ar' and 'ranlib', and libtz.a is now built locally before being
4203    installed.  (Thanks to Michael Forney.)
4204
4205    A dependency typo in the 'zdump' rule has been fixed.
4206    (Thanks to Andrew Paprocki.)
4207
4208    The Makefile has been simplified by assuming that 'mkdir -p' and 'cp -f'
4209    work as specified by POSIX.2-1992 or later; this is portable nowadays.
4210
4211    'make clean' no longer removes 'leapseconds', since it's
4212    host-independent and is part of the distribution.
4213
4214    The unused makefile macros TZCSRCS, TZDSRCS, DATESRCS have been removed.
4215
4216  Changes affecting documentation and commentary
4217
4218    tz-link.htm now mentions TC TIMEZONE's draft time zone service protocol
4219    (thanks to Mike Douglass) and TimezoneJS.Date (thanks to Jim Fehrle).
4220
4221    Update URLs in tz-link page.  Add URLs for Microsoft Windows, since
4222    8.1 introduces tz support.  Remove URLs for Tru64 and UnixWare (no
4223    longer maintained) and for old advisories.  SOFA now does C.
4224
4225Release 2013g - 2013-09-30 21:08:26 -0700
4226
4227  Changes affecting current and near-future timestamps
4228
4229    Morocco now observes DST from the last Sunday in March to the last
4230    Sunday in October, not April to September respectively.  (Thanks
4231    to Steffen Thorsen.)
4232
4233  Changes affecting 'zic'
4234
4235    'zic' now runs on platforms that lack both hard links and symlinks.
4236    (Thanks to Theo Veenker for reporting the problem, for MinGW.)
4237    Also, fix some bugs on platforms that lack hard links but have symlinks.
4238
4239    'zic -v' again warns that Asia/Tehran has no POSIX environment variable
4240    to predict the far future, fixing a bug introduced in 2013e.
4241
4242  Changes affecting the build procedure
4243
4244    The 'leapseconds' file is again put into the tzdata tarball.
4245    Also, 'leapseconds.awk', so tzdata is self-contained.  (Thanks to
4246    Matt Burgess and Ian Abbott.)  The timestamps of these and other
4247    dependent files in tarballs are adjusted more consistently.
4248
4249  Changes affecting documentation and commentary
4250
4251    The README file is now part of the data tarball as well as the code.
4252    It now states that files are public domain unless otherwise specified.
4253    (Thanks to Andrew Main (Zefram) for asking for clarifications.)
4254    Its details about the 1989 release moved to a place of honor near
4255    the end of NEWS.
4256
4257
4258Release 2013f - 2013-09-24 23:37:36 -0700
4259
4260  Changes affecting near-future timestamps
4261
4262    Tocantins will very likely not observe DST starting this spring.
4263    (Thanks to Steffen Thorsen.)
4264
4265    Jordan will likely stay at UT +03 indefinitely, and will not fall
4266    back this fall.
4267
4268    Palestine will fall back at 00:00, not 01:00.  (Thanks to Steffen Thorsen.)
4269
4270  Changes affecting API
4271
4272    The types of the global variables 'timezone' and 'altzone' (if present)
4273    have been changed back to 'long'.  This is required for 'timezone'
4274    by POSIX, and for 'altzone' by common practice, e.g., Solaris 11.
4275    These variables were originally 'long' in the tz code, but were
4276    mistakenly changed to 'time_t' in 1987; nobody reported the
4277    incompatibility until now.  The difference matters on x32, where
4278    'long' is 32 bits and 'time_t' is 64.  (Thanks to Elliott Hughes.)
4279
4280  Changes affecting the build procedure
4281
4282    Avoid long strings in leapseconds.awk to work around a mawk bug.
4283    (Thanks to Cyril Baurand.)
4284
4285  Changes affecting documentation and commentary
4286
4287    New file 'NEWS' that contains release notes like this one.
4288
4289    Paraguay's law does not specify DST transition time; 00:00 is customary.
4290    (Thanks to Waldemar Villamayor-Venialbo.)
4291
4292    Minor capitalization fixes.
4293
4294  Changes affecting version-control only
4295
4296    The experimental GitHub repository now contains annotated and
4297    signed tags for recent releases, e.g., '2013e' for Release 2013e.
4298    Releases are tagged starting with 2012e; earlier releases were
4299    done differently, and tags would either not have a simple name or
4300    not exactly match what was released.
4301
4302    'make set-timestamps' is now simpler and a bit more portable.
4303
4304
4305Release 2013e - 2013-09-19 23:50:04 -0700
4306
4307  Changes affecting near-future timestamps
4308
4309    This year Fiji will start DST on October 27, not October 20.
4310    (Thanks to David Wheeler for the heads-up.)  For now, guess that
4311    Fiji will continue to spring forward the Sunday before the fourth
4312    Monday in October.
4313
4314  Changes affecting current and future time zone abbreviations
4315
4316    Use WIB/WITA/WIT rather than WIT/CIT/EIT for alphabetic Indonesian
4317    time zone abbreviations since 1932.  (Thanks to George Ziegler,
4318    Priyadi Iman Nurcahyo, Zakaria, Jason Grimes, Martin Pitt, and
4319    Benny Lin.)  This affects Asia/Dili, Asia/Jakarta, Asia/Jayapura,
4320    Asia/Makassar, and Asia/Pontianak.
4321
4322    Use ART (UT -03, standard time), rather than WARST (also -03, but
4323    daylight saving time) for San Luis, Argentina since 2009.
4324
4325  Changes affecting Godthåb timestamps after 2037 if version mismatch
4326
4327    Allow POSIX-like TZ strings where the transition time's hour can
4328    range from -167 through 167, instead of the POSIX-required 0
4329    through 24.  E.g., TZ='FJT-12FJST,M10.3.1/146,M1.3.4/75' for the
4330    new Fiji rules.  This is a more compact way to represent
4331    far-future timestamps for America/Godthab, America/Santiago,
4332    Antarctica/Palmer, Asia/Gaza, Asia/Hebron, Asia/Jerusalem,
4333    Pacific/Easter, and Pacific/Fiji.  Other zones are unaffected by
4334    this change.  (Derived from a suggestion by Arthur David Olson.)
4335
4336    Allow POSIX-like TZ strings where daylight saving time is in
4337    effect all year.  E.g., TZ='WART4WARST,J1/0,J365/25' for Western
4338    Argentina Summer Time all year.  This supports a more compact way
4339    to represent the 2013d data for America/Argentina/San_Luis.
4340    Because of the change for San Luis noted above this change does not
4341    affect the current data.  (Thanks to Andrew Main (Zefram) for
4342    suggestions that improved this change.)
4343
4344    Where these two TZ changes take effect, there is a minor extension
4345    to the tz file format in that it allows new values for the
4346    embedded TZ-format string, and the tz file format version number
4347    has therefore been increased from 2 to 3 as a precaution.
4348    Version-2-based client code should continue to work as before for
4349    all timestamps before 2038.  Existing version-2-based client code
4350    (tzcode, GNU/Linux, Solaris) has been tested on version-3-format
4351    files, and typically works in practice even for timestamps after
4352    2037; the only known exception is America/Godthab.
4353
4354  Changes affecting timestamps before 1970
4355
4356    Pacific/Johnston is now a link to Pacific/Honolulu.  This corrects
4357    some errors before 1947.
4358
4359    Some zones have been turned into links, when they differ from existing
4360    zones only in older data entries that were likely invented or that
4361    differ only in LMT or transitions from LMT.  These changes affect
4362    only timestamps before 1943.  The affected zones are:
4363    Africa/Juba, America/Anguilla, America/Aruba, America/Dominica,
4364    America/Grenada, America/Guadeloupe, America/Marigot,
4365    America/Montserrat, America/St_Barthelemy, America/St_Kitts,
4366    America/St_Lucia, America/St_Thomas, America/St_Vincent,
4367    America/Tortola, and Europe/Vaduz.  (Thanks to Alois Treindl for
4368    confirming that the old Europe/Vaduz zone was wrong and the new
4369    link is better for WWII-era times.)
4370
4371    Change Kingston Mean Time from -5:07:12 to -5:07:11.  This affects
4372    America/Cayman, America/Jamaica and America/Grand_Turk timestamps
4373    from 1890 to 1912.
4374
4375    Change the UT offset of Bern Mean Time from 0:29:44 to 0:29:46.
4376    This affects Europe/Zurich timestamps from 1853 to 1894.  (Thanks
4377    to Alois Treindl.)
4378
4379    Change the date of the circa-1850 Zurich transition from 1849-09-12
4380    to 1853-07-16, overriding Shanks with data from Messerli about
4381    postal and telegraph time in Switzerland.
4382
4383  Changes affecting time zone abbreviations before 1970
4384
4385    For Asia/Jakarta, use BMT (not JMT) for mean time from 1923 to 1932,
4386    as Jakarta was called Batavia back then.
4387
4388  Changes affecting API
4389
4390    The 'zic' command now outputs a dummy transition when far-future
4391    data can't be summarized using a TZ string, and uses a 402-year
4392    window rather than a 400-year window.  For the current data, this
4393    affects only the Asia/Tehran file.  It does not affect any of the
4394    timestamps that this file represents, so zdump outputs the same
4395    information as before.  (Thanks to Andrew Main (Zefram).)
4396
4397    The 'date' command has a new '-r' option, which lets you specify
4398    the integer time to display, a la FreeBSD.
4399
4400    The 'tzselect' command has two new options '-c' and '-n', which lets you
4401    select a zone based on latitude and longitude.
4402
4403    The 'zic' command's '-v' option now warns about constructs that
4404    require the new version-3 binary file format.  (Thanks to Arthur
4405    David Olson for the suggestion.)
4406
4407    Support for floating-point time_t has been removed.
4408    It was always dicey, and POSIX no longer requires it.
4409    (Thanks to Eric Blake for suggesting to the POSIX committee to
4410    remove it, and thanks to Alan Barrett, Clive D.W. Feather, Andy
4411    Heninger, Arthur David Olson, and Alois Treindl, for reporting
4412    bugs and elucidating some of the corners of the old floating-point
4413    implementation.)
4414
4415    The signatures of 'offtime', 'timeoff', and 'gtime' have been
4416    changed back to the old practice of using 'long' to represent UT
4417    offsets.  This had been inadvertently and mistakenly changed to
4418    'int_fast32_t'.  (Thanks to Christos Zoulas.)
4419
4420    The code avoids undefined behavior on integer overflow in some
4421    more places, including gmtime, localtime, mktime and zdump.
4422
4423  Changes affecting the zdump utility
4424
4425    zdump now outputs "UT" when referring to Universal Time, not "UTC".
4426    "UTC" does not make sense for timestamps that predate the introduction
4427    of UTC, whereas "UT", a more generic term, does.  (Thanks to Steve Allen
4428    for clarifying UT vs UTC.)
4429
4430  Data changes affecting behavior of tzselect and similar programs
4431
4432    Country code BQ is now called the more common name "Caribbean Netherlands"
4433    rather than the more official "Bonaire, St Eustatius & Saba".
4434
4435    Remove from zone.tab the names America/Montreal, America/Shiprock,
4436    and Antarctica/South_Pole, as they are equivalent to existing
4437    same-country-code zones for post-1970 timestamps.  The data entries for
4438    these names are unchanged, so the names continue to work as before.
4439
4440  Changes affecting code internals
4441
4442    zic -c now runs way faster on 64-bit hosts when given large numbers.
4443
4444    zic now uses vfprintf to avoid allocating and freeing some memory.
4445
4446    tzselect now computes the list of continents from the data,
4447    rather than have it hard-coded.
4448
4449    Minor changes pacify GCC 4.7.3 and GCC 4.8.1.
4450
4451  Changes affecting the build procedure
4452
4453    The 'leapseconds' file is now generated automatically from a
4454    new file 'leap-seconds.list', which is a copy of
4455    <ftp://ftp.nist.gov/pub/time/leap-seconds.list>
4456    A new source file 'leapseconds.awk' implements this.
4457    The goal is simplification of the future maintenance of 'leapseconds'.
4458
4459    When building the 'posix' or 'right' subdirectories, if the
4460    subdirectory would be a copy of the default subdirectory, it is
4461    now made a symbolic link if that is supported.  This saves about
4462    2 MB of file system space.
4463
4464    The links America/Shiprock and Antarctica/South_Pole have been
4465    moved to the 'backward' file.  This affects only nondefault builds
4466    that omit 'backward'.
4467
4468  Changes affecting version-control only
4469
4470    .gitignore now ignores 'date'.
4471
4472  Changes affecting documentation and commentary
4473
4474    Changes to the 'tzfile' man page
4475
4476      It now mentions that the binary file format may be extended in
4477      future versions by appending data.
4478
4479      It now refers to the 'zdump' and 'zic' man pages.
4480
4481    Changes to the 'zic' man page
4482
4483      It lists conditions that elicit a warning with '-v'.
4484
4485      It says that the behavior is unspecified when duplicate names
4486      are given, or if the source of one link is the target of another.
4487
4488      Its examples are updated to match the latest data.
4489
4490      The definition of white space has been clarified slightly.
4491      (Thanks to Michael Deckers.)
4492
4493    Changes to the 'Theory' file
4494
4495      There is a new section about the accuracy of the tz database,
4496      describing the many ways that errors can creep in, and
4497      explaining why so many of the pre-1970 timestamps are wrong or
4498      misleading (thanks to Steve Allen, Lester Caine, and Garrett
4499      Wollman for discussions that contributed to this).
4500
4501      The 'Theory' file describes LMT better (this follows a
4502      suggestion by Guy Harris).
4503
4504      It refers to the 2013 edition of POSIX rather than the 2004 edition.
4505
4506      It's mentioned that excluding 'backward' should not affect the
4507      other data, and it suggests at least one zone.tab name per
4508      inhabited country (thanks to Stephen Colebourne).
4509
4510      Some longstanding restrictions on names are documented, e.g.,
4511      'America/New_York' precludes 'America/New_York/Bronx'.
4512
4513      It gives more reasons for the 1970 cutoff.
4514
4515      It now mentions which time_t variants are supported, such as
4516      signed integer time_t.  (Thanks to Paul Goyette for reporting
4517      typos in an experimental version of this change.)
4518
4519      (Thanks to Philip Newton for correcting typos in these changes.)
4520
4521    Documentation and commentary is more careful to distinguish UT in
4522    general from UTC in particular.  (Thanks to Steve Allen.)
4523
4524    Add a better source for the Zurich 1894 transition.
4525    (Thanks to Pierre-Yves Berger.)
4526
4527    Update shapefile citations in tz-link.htm.  (Thanks to Guy Harris.)
4528
4529
4530Release 2013d - 2013-07-05 07:38:01 -0700
4531
4532  Changes affecting future timestamps:
4533
4534    Morocco's midsummer transitions this year are July 7 and August 10,
4535    not July 9 and August 8.  (Thanks to Andrew Paprocki.)
4536
4537    Israel now falls back on the last Sunday of October.
4538    (Thanks to Ephraim Silverberg.)
4539
4540  Changes affecting past timestamps:
4541
4542    Specify Jerusalem's location more precisely; this changes the pre-1880
4543    times by 2 s.
4544
4545  Changing affecting metadata only:
4546
4547    Fix typos in the entries for country codes BQ and SX.
4548
4549  Changes affecting code:
4550
4551    Rework the code to fix a bug with handling Australia/Macquarie on
4552    32-bit hosts (thanks to Arthur David Olson).
4553
4554    Port to platforms like NetBSD, where time_t can be wider than long.
4555
4556    Add support for testing time_t types other than the system's.
4557    Run 'make check_time_t_alternatives' to try this out.
4558    Currently, the tests fail for unsigned time_t;
4559    this should get fixed at some point.
4560
4561  Changes affecting documentation and commentary:
4562
4563    Deemphasize the significance of national borders.
4564
4565    Update the zdump man page.
4566
4567    Remove obsolete NOID comment (thanks to Denis Excoffier).
4568
4569    Update several URLs and comments in the web pages.
4570
4571    Spelling fixes (thanks to Kevin Lyda and Jonathan Leffler).
4572
4573    Update URL for CLDR Zone->Tzid table (thanks to Yoshito Umaoka).
4574
4575
4576Release 2013c - 2013-04-19 16:17:40 -0700
4577
4578  Changes affecting current and future timestamps:
4579
4580    Palestine observed DST starting March 29, 2013.  (Thanks to
4581    Steffen Thorsen.)  From 2013 on, Gaza and Hebron both observe DST,
4582    with the predicted rules being the last Thursday in March at 24:00
4583    to the first Friday on or after September 21 at 01:00.
4584
4585    Assume that the recent change to Paraguay's DST rules is permanent,
4586    by moving the end of DST to the 4th Sunday in March every year.
4587    (Thanks to Carlos Raúl Perasso.)
4588
4589  Changes affecting past timestamps:
4590
4591    Fix some historical data for Palestine to agree with that of
4592    timeanddate.com, as follows:
4593
4594	  The spring 2008 change in Gaza and Hebron was on 00:00 Mar 28, not
4595	  00:00 Apr 1.
4596
4597	  The fall 2009 change in Gaza and Hebron on Sep 4 was at 01:00, not
4598	  02:00.
4599
4600	  The spring 2010 change in Hebron was 00:00 Mar 26, not 00:01 Mar 27.
4601
4602	  The spring 2011 change in Gaza was 00:01 Apr 1, not 12:01 Apr 2.
4603
4604	  The spring 2011 change in Hebron on Apr 1 was at 00:01, not 12:01.
4605
4606	  The fall 2011 change in Hebron on Sep 30 was at 00:00, not 03:00.
4607
4608    Fix times of habitation for Macquarie to agree with the Tasmania
4609    Parks & Wildlife Service history, which indicates that permanent
4610    habitation was 1899-1919 and 1948 on.
4611
4612  Changing affecting metadata only:
4613
4614    Macquarie Island is politically part of Australia, not Antarctica.
4615    (Thanks to Tobias Conradi.)
4616
4617    Sort Macquarie more consistently with other parts of Australia.
4618    (Thanks to Tim Parenti.)
4619
4620
4621Release 2013b - 2013-03-10 22:33:40 -0700
4622
4623  Changes affecting current and future timestamps:
4624
4625    Haiti uses US daylight-saving rules this year, and presumably future years.
4626    This changes timestamps starting today.  (Thanks to Steffen Thorsen.)
4627
4628    Paraguay will end DST on March 24 this year.
4629    (Thanks to Steffen Thorsen.)  For now, assume it's just this year.
4630
4631    Morocco does not observe DST during Ramadan;
4632    try to predict Ramadan in Morocco as best we can.
4633    (Thanks to Erik Homoet for the heads-up.)
4634
4635  Changes affecting commentary:
4636
4637    Update URLs in tz-link page.  Add URLs for webOS, BB10, iOS.
4638    Update URL for Solaris.  Mention Internet RFC 6557.
4639    Update Internet RFCs 2445->5545, 2822->5322.
4640    Switch from FTP to HTTP for Internet RFCs.
4641
4642
4643Release 2013a - 2013-02-27 09:20:35 -0800
4644
4645  Change affecting binary data format:
4646
4647    The zone offset at the end of version-2-format zone files is now
4648    allowed to be 24:00, as per POSIX.1-2008.  (Thanks to Arthur David Olson.)
4649
4650  Changes affecting current and future timestamps:
4651
4652    Chile's 2013 rules, and we guess rules for 2014 and later, will be
4653    the same as 2012, namely Apr Sun>=23 03:00 UTC to Sep Sun>=2 04:00 UTC.
4654    (Thanks to Steffen Thorsen and Robert Elz.)
4655
4656    New Zones Asia/Khandyga, Asia/Ust-Nera, Europe/Busingen.
4657    (Thanks to Tobias Conradi and Arthur David Olson.)
4658
4659  Many changes affect historical timestamps before 1940.
4660  These were deduced from: Milne J. Civil time. Geogr J. 1899
4661  Feb;13(2):173-94 <https://www.jstor.org/stable/1774359>.
4662
4663  Changes affecting the code:
4664
4665    Fix zic bug that mishandled Egypt's 2010 changes (this also affected
4666    the data).  (Thanks to Arthur David Olson.)
4667
4668    Fix localtime bug when time_t is unsigned and data files were generated
4669    by a signed time_t system.  (Thanks to Doug Bailey for reporting and
4670    to Arthur David Olson for fixing.)
4671
4672    Allow the email address for bug reports to be set by the packager.
4673    The default is tz@iana.org, as before.  (Thanks to Joseph S. Myers.)
4674
4675    Update HTML checking to be compatible with Ubuntu 12.10.
4676
4677    Check that files are a safe subset of ASCII.  At some point we may
4678    relax this requirement to a safe subset of UTF-8.  Without the
4679    check, some non-UTF-8 encodings were leaking into the distribution.
4680
4681  Commentary changes:
4682
4683    Restore a comment about copyright notices that was inadvertently deleted.
4684    (Thanks to Arthur David Olson.)
4685
4686    Improve the commentary about which districts observe what times
4687    in Russia.  (Thanks to Oscar van Vlijmen and Arthur David Olson.)
4688
4689    Add web page links to tz.js.
4690
4691    Add "Run by the Monkeys" to tz-art.  (Thanks to Arthur David Olson.)
4692
4693
4694Release 2012j - 2012-11-12 18:34:49 -0800
4695
4696  Libya moved to CET this weekend, but with DST planned next year.
4697  (Thanks to Even Scharning, Steffen Thorsen, and Tim Parenti.)
4698
4699  Signatures now have the extension .asc, not .sign, as that's more
4700  standard.  (Thanks to Phil Pennock.)
4701
4702  The output of 'zdump --version', and of 'zic --version', now
4703  uses a format that is more typical for --version.
4704  (Thanks to Joseph S. Myers.)
4705
4706  The output of 'tzselect --help', 'zdump --help', and 'zic --help'
4707  now uses tz@iana.org rather than the old elsie address.
4708
4709  zic -v now complains about abbreviations that are less than 3
4710  or more than 6 characters, as per POSIX.  Formerly, it checked
4711  for abbreviations that were more than 3.
4712
4713  'make public' no longer puts its temporary directory under /tmp,
4714  and uses the just-built zic rather than the system zic.
4715
4716  Various fixes to documentation and commentary.
4717
4718
4719Release 2012i - 2012-11-03 12:57:09 -0700
4720
4721  Cuba switches from DST tomorrow at 01:00.  (Thanks to Steffen Thorsen.)
4722
4723  Linker flags can now be specified via LDFLAGS.
4724  AWK now defaults to 'awk', not 'nawk'.
4725  The shell in tzselect now defaults to /bin/bash, but this can
4726  be overridden by specifying KSHELL.
4727  The main web page now mentions the unofficial GitHub repository.
4728  (Thanks to Mike Frysinger.)
4729
4730  Tarball signatures can now be built by running 'make signatures'.
4731  There are also new makefile rules 'tarballs', 'check_public', and
4732  separate makefile rules for each tarball and signature file.
4733  A few makefile rules are now more portable to strict POSIX.
4734
4735  The main web page now lists the canonical IANA URL.
4736
4737
4738Release 2012h - 2012-10-26 22:49:10 -0700
4739
4740  Bahia no longer has DST.  (Thanks to Kelley Cook.)
4741
4742  Tocantins has DST.  (Thanks to Rodrigo Severo.)
4743
4744  Israel has new DST rules next year.  (Thanks to Ephraim Silverberg.)
4745
4746  Jordan stays on DST this winter.  (Thanks to Steffen Thorsen.)
4747
4748  Web page updates.
4749
4750  More C modernization, except that at Arthur David Olson's suggestion
4751  the instances of 'register' were kept.
4752
4753
4754Release 2012g - 2012-10-17 20:59:45 -0700
4755
4756  Samoa fall 2012 and later.  (Thanks to Nicholas Pereira and Robert Elz.)
4757
4758  Palestine fall 2012.  (Thanks to Steffen Thorsen.)
4759
4760  Assume C89.
4761
4762  To attack the version-number problem, this release ships the file
4763  'Makefile' (which contains the release number) in both the tzcode and
4764  the tzdata tarballs.  The two Makefiles are identical, and should be
4765  identical in any matching pair of tarballs, so it shouldn't matter
4766  which order you extract the tarballs.  Perhaps we can come up with a
4767  better version-number scheme at some point; this scheme does have the
4768  virtue of not adding more files.
4769
4770
4771Release 2012f - 2012-09-12 23:17:03 -0700
4772
4773  * australasia (Pacific/Fiji): Fiji DST is October 21 through January
4774    20 this year.  (Thanks to Steffen Thorsen.)
4775
4776
4777Release 2012e - 2012-08-02 20:44:55 -0700
4778
4779  * australasia (Pacific/Fakaofo): Tokelau is UT +13, not +14.
4780    (Thanks to Steffen Thorsen.)
4781
4782  * Use a single version number for both code and data.
4783
4784  * .gitignore: New file.
4785
4786  * Remove trailing white space.
4787
4788
4789Release code2012c-data2012d - 2012-07-19 16:35:33 -0700
4790
4791  Changes for Morocco's timestamps, which take effect in a couple of
4792  hours, along with infrastructure changes to accommodate how the tz
4793  code and data are released on IANA.
4794
4795
4796Release data2012c - 2012-03-27 12:17:25 -0400
4797
4798  africa
4799	Summer time changes for Morocco (to start late April 2012)
4800
4801  asia
4802	Changes for 2012 for Gaza & the West Bank (Hebron) and Syria
4803
4804  northamerica
4805	Haiti following US/Canada rules for 2012 (and we're assuming,
4806	for now anyway, for the future).
4807
4808
4809Release 2012b - 2012-03-02 12:29:15 +0700
4810
4811  There is just one change to tzcode2012b (compared with 2012a):
4812  the Makefile that was accidentally included with 2012a has been
4813  replaced with the version that should have been there, which is
4814  identical with the previous version (from tzcode2011i).
4815
4816  There are just two changes in tzdata2012b compared with 2012a.
4817
4818  Most significantly, summer time in Cuba has been delayed 3 weeks
4819  (now starts April 1 rather than March 11).   Since Mar 11 (the old start
4820  date, as listed in 2012a) is just a little over a week away, this
4821  change is urgent.
4822
4823  Less importantly, an excess tab in one of the changes in zone.tab
4824  in 2012a has been removed.
4825
4826
4827Release 2012a - 2012-03-01 18:28:10 +0700
4828
4829  The changes in tzcode2012a (compared to the previous version, 2011i)
4830  are entirely to the README and tz-art.htm and tz-link.htm files, if
4831  none of those concern you, you can ignore the code update.  The changes
4832  reflect the changed addresses for the mailing list and the code and
4833  data distribution points & methods (and a link to DateTime::TimeZone::Tzfile
4834  has been added to tz-link.htm).
4835
4836  In tzdata2012a (compared to the previous release, which was 2011n)
4837  the major changes are:
4838	Chile 2011/2012 and 2012/2013 summer time date adjustments.
4839	Falkland Islands onto permanent summer time (we're assuming for the
4840		foreseeable future, though 2012 is all we're fairly certain of.)
4841	Armenia has abolished Summer Time.
4842	Tokelau jumped the International Date Line back last December
4843		(just the same as their near neighbour, Samoa).
4844	America/Creston is a new zone for a small area of British Columbia
4845	There will be a leapsecond 2012-06-30 23:59:60 UTC.
4846
4847  Other minor changes are:
4848	Corrections to 1918 Canadian summer time end dates.
4849	Updated URL for UK time zone history (in comments)
4850	A few typos in Le Corre's list of free French place names (comments)
4851
4852
4853Release data2011n - 2011-10-30 14:57:54 +0700
4854
4855  There are three changes of note - most urgently, Cuba (America/Havana)
4856  has extended summer time by two weeks, now to end on Nov 13, rather than
4857  the (already past) Oct 30.   Second, the Pridnestrovian Moldavian Republic
4858  (Europe/Tiraspol) decided not to split from the rest of Moldova after
4859  all, and consequently that zone has been removed (again) and reinstated
4860  in the "backward" file as a link to Europe/Chisinau.   And third, the
4861  end date for Fiji's summer time this summer was moved forward from the
4862  earlier planned Feb 26, to Jan 22.
4863
4864  Apart from that, Moldova (MD) returns to a single entry in zone.tab
4865  (and the incorrect syntax that was in the 2011m version of that file
4866  is so fixed - it would have been fixed in a different way had this
4867  change not happened - that's the "missing" sccs version id).
4868
4869
4870Release data2011m - 2011-10-24 21:42:16 +0700
4871
4872  In particular, the typos in comments in the data (2011-11-17 should have
4873  been 2011-10-17 as Alan Barrett noted, and spelling of Tiraspol that
4874  Tim Parenti noted) have been fixed, and the change for Ukraine has been
4875  made in all 4 Ukrainian zones, rather than just Europe/Kiev
4876  (again, thanks to Tim Parenti, and also Denys Gavrysh).
4877
4878  In addition, I added Europe/Tiraspol to zone.tab.
4879
4880  This time, all the files have new version numbers...  (including the files
4881  otherwise unchanged in 2011m that were changed in 2011l but didn't get new
4882  version numbers there...)
4883
4884
4885Release data2011l - 2011-10-10 11:15:43 +0700
4886
4887  There are just 2 changes that cause different generated tzdata files from
4888  zic, to Asia/Hebron and Pacific/Fiji - the possible change for Bahia, Brazil
4889  is included, but commented out.  Compared with the diff I sent out last week,
4890  this version also includes attributions for the sources for the changes
4891  (in much the same format as ado used, but the html tags have not been
4892  checked, verified, or used in any way at all, so if there are errors there,
4893  please let me know.)
4894
4895
4896Release data2011k - 2011-09-20 17:54:03 -0400
4897
4898  [not summarized]
4899
4900
4901Release data2011j - 2011-09-12 09:22:49 -0400
4902
4903  (contemporary changes for Samoa; past changes for Kenya, Uganda, and
4904  Tanzania); there are also two spelling corrections to comments in
4905  the australasia file (with thanks to Christos Zoulas).
4906
4907
4908Release 2011i - 2011-08-29 05:56:32 -0400
4909
4910  [not summarized]
4911
4912
4913Release data2011h - 2011-06-15 18:41:48 -0400
4914
4915  Russia and Curaçao changes
4916
4917
4918Release 2011g - 2011-04-25 09:07:22 -0400
4919
4920  update the rules for Egypt to reflect its abandonment of DST this year
4921
4922
4923Release 2011f - 2011-04-06 17:14:53 -0400
4924
4925  [not summarized]
4926
4927
4928Release 2011e - 2011-03-31 16:04:38 -0400
4929
4930  Morocco, Chile, and tz-link changes
4931
4932
4933Release 2011d - 2011-03-14 09:18:01 -0400
4934
4935  changes that impact present-day timestamps in Cuba, Samoa, and Turkey
4936
4937
4938Release 2011c - 2011-03-07 09:30:09 -0500
4939
4940  These do affect current timestamps in Chile and Annette Island, Canada.
4941
4942
4943Release 2011b - 2011-02-07 08:44:50 -0500
4944
4945  [not summarized]
4946
4947
4948Release 2011a - 2011-01-24 10:30:16 -0500
4949
4950  [not summarized]
4951
4952
4953Release data2010o - 2010-11-01 09:18:23 -0400
4954
4955  change to the end of DST in Fiji in 2011
4956
4957
4958Release 2010n - 2010-10-25 08:19:17 -0400
4959
4960  [not summarized]
4961
4962
4963Release 2010m - 2010-09-27 09:24:48 -0400
4964
4965  Hong Kong, Vostok, and zic.c changes
4966
4967
4968Release 2010l - 2010-08-16 06:57:25 -0400
4969
4970  [not summarized]
4971
4972
4973Release 2010k - 2010-07-26 10:42:27 -0400
4974
4975  [not summarized]
4976
4977
4978Release 2010j - 2010-05-10 09:07:48 -0400
4979
4980  changes for Bahía de Banderas and for version naming
4981
4982
4983Release data2010i - 2010-04-16 18:50:45 -0400
4984
4985  the end of DST in Morocco on 2010-08-08
4986
4987
4988Release data2010h - 2010-04-05 09:58:56 -0400
4989
4990  [not summarized]
4991
4992
4993Release data2010g - 2010-03-24 11:14:53 -0400
4994
4995  [not summarized]
4996
4997
4998Release 2010f - 2010-03-22 09:45:46 -0400
4999
5000  [not summarized]
5001
5002
5003Release data2010e - 2010-03-08 14:24:27 -0500
5004
5005  corrects the Dhaka bug found by Danvin Ruangchan
5006
5007
5008Release data2010d - 2010-03-06 07:26:01 -0500
5009
5010  [not summarized]
5011
5012
5013Release 2010c - 2010-03-01 09:20:58 -0500
5014
5015  changes including KRE's suggestion for earlier initialization of
5016  "goahead" and "goback" structure elements
5017
5018
5019Release code2010a - 2010-02-16 10:40:04 -0500
5020
5021  [not summarized]
5022
5023
5024Release data2010b - 2010-01-20 12:37:01 -0500
5025
5026  Mexico changes
5027
5028
5029Release data2010a - 2010-01-18 08:30:04 -0500
5030
5031  changes to Dhaka
5032
5033
5034Release data2009u - 2009-12-26 08:32:28 -0500
5035
5036  changes to DST in Bangladesh
5037
5038
5039Release 2009t - 2009-12-21 13:24:27 -0500
5040
5041  [not summarized]
5042
5043
5044Release data2009s - 2009-11-14 10:26:32 -0500
5045
5046  (cosmetic) Antarctica change and the DST-in-Fiji-in-2009-and-2010 change
5047
5048
5049Release 2009r - 2009-11-09 10:10:31 -0500
5050
5051  "antarctica" and "tz-link.htm" changes
5052
5053
5054Release 2009q - 2009-11-02 09:12:40 -0500
5055
5056  with two corrections as reported by Eric Muller and Philip Newton
5057
5058
5059Release data2009p - 2009-10-23 15:05:27 -0400
5060
5061  Argentina (including San Luis) changes (with the correction from
5062  Mariano Absatz)
5063
5064
5065Release data2009o - 2009-10-14 16:49:38 -0400
5066
5067  Samoa (commentary only), Pakistan, and Bangladesh changes
5068
5069
5070Release data2009n - 2009-09-22 15:13:38 -0400
5071
5072  added commentary for Argentina and a change to the end of DST in
5073  2009 in Pakistan
5074
5075
5076Release data2009m - 2009-09-03 10:23:43 -0400
5077
5078  Samoa and Palestine changes
5079
5080
5081Release data2009l - 2009-08-14 09:13:07 -0400
5082
5083  Samoa (comments only) and Egypt
5084
5085
5086Release 2009k - 2009-07-20 09:46:08 -0400
5087
5088  [not summarized]
5089
5090
5091Release data2009j - 2009-06-15 06:43:59 -0400
5092
5093  Bangladesh change (with a short turnaround since the DST change is
5094  impending)
5095
5096
5097Release 2009i - 2009-06-08 09:21:22 -0400
5098
5099  updating for DST in Bangladesh this year
5100
5101
5102Release 2009h - 2009-05-26 09:19:14 -0400
5103
5104  [not summarized]
5105
5106
5107Release data2009g - 2009-04-20 16:34:07 -0400
5108
5109  Cairo
5110
5111
5112Release data2009f - 2009-04-10 11:00:52 -0400
5113
5114  correct DST in Pakistan
5115
5116
5117Release 2009e - 2009-04-06 09:08:11 -0400
5118
5119  [not summarized]
5120
5121
5122Release 2009d - 2009-03-23 09:38:12 -0400
5123
5124  Morocco, Tunisia, Argentina, and American Astronomical Society changes
5125
5126
5127Release data2009c - 2009-03-16 09:47:51 -0400
5128
5129  change to the start of Cuban DST
5130
5131
5132Release 2009b - 2009-02-09 11:15:22 -0500
5133
5134  [not summarized]
5135
5136
5137Release 2009a - 2009-01-21 10:09:39 -0500
5138
5139  [not summarized]
5140
5141
5142Release data2008i - 2008-10-21 12:10:25 -0400
5143
5144  southamerica and zone.tab files, with Argentina DST rule changes and
5145  United States zone reordering and recommenting
5146
5147
5148Release 2008h - 2008-10-13 07:33:56 -0400
5149
5150  [not summarized]
5151
5152
5153Release 2008g - 2008-10-06 09:03:18 -0400
5154
5155  Fix a broken HTML anchor and update Brazil's DST transitions;
5156  there's also a slight reordering of information in tz-art.htm.
5157
5158
5159Release data2008f - 2008-09-09 22:33:26 -0400
5160
5161  [not summarized]
5162
5163
5164Release 2008e - 2008-07-28 14:11:17 -0400
5165
5166  changes by Arthur David Olson and Jesper Nørgaard Welen
5167
5168
5169Release data2008d - 2008-07-07 09:51:38 -0400
5170
5171  changes by Arthur David Olson, Paul Eggert, and Rodrigo Severo
5172
5173
5174Release data2008c - 2008-05-19 17:48:03 -0400
5175
5176  Pakistan, Morocco, and Mongolia
5177
5178
5179Release data2008b - 2008-03-24 08:30:59 -0400
5180
5181  including renaming Asia/Calcutta to Asia/Kolkata, with a backward
5182  link provided
5183
5184
5185Release 2008a - 2008-03-08 05:42:16 -0500
5186
5187  [not summarized]
5188
5189
5190Release 2007k - 2007-12-31 10:25:22 -0500
5191
5192  most importantly, changes to the "southamerica" file based on
5193  Argentina's readoption of daylight saving time
5194
5195
5196Release 2007j - 2007-12-03 09:51:01 -0500
5197
5198  1. eliminate the "P" (parameter) macro;
5199
5200  2. the "noncontroversial" changes circulated on the time zone
5201  mailing list (less the changes to "logwtmp.c");
5202
5203  3. eliminate "too many transition" errors when "min" is used in time
5204  zone rules;
5205
5206  4. changes by Paul Eggert (including updated information for Venezuela).
5207
5208
5209Release data2007i - 2007-10-30 10:28:11 -0400
5210
5211  changes for Cuba and Syria
5212
5213
5214Release 2007h - 2007-10-01 10:05:51 -0400
5215
5216  changes by Paul Eggert, as well as an updated link to the ICU
5217  project in tz-link.htm
5218
5219
5220Release 2007g - 2007-08-20 10:47:59 -0400
5221
5222  changes by Paul Eggert
5223
5224  The "leapseconds" file has been updated to incorporate the most
5225  recent International Earth Rotation and Reference Systems Service
5226  (IERS) bulletin.
5227
5228  There's an addition to tz-art.htm regarding the television show "Medium".
5229
5230
5231Release 2007f - 2007-05-07 10:46:46 -0400
5232
5233  changes by Paul Eggert (including Haiti, Turks and Caicos, and New
5234  Zealand)
5235
5236  changes to zic.c to allow hour values greater than 24 (along with
5237  Paul's improved time value overflow checking)
5238
5239
5240Release 2007e - 2007-04-02 10:11:52 -0400
5241
5242  Syria and Honduras changes by Paul Eggert
5243
5244  zic.c variable renaming changes by Arthur David Olson
5245
5246
5247Release 2007d - 2007-03-20 08:48:30 -0400
5248
5249  changes by Paul Eggert
5250
5251  the elimination of white space at the ends of lines
5252
5253
5254Release 2007c - 2007-02-26 09:09:37 -0500
5255
5256  changes by Paul Eggert
5257
5258
5259Release 2007b - 2007-02-12 09:34:20 -0500
5260
5261  Paul Eggert's proposed change to the quotation handling logic in zic.c.
5262
5263  changes to the commentary in "leapseconds" reflecting the IERS
5264  announcement that there is to be no positive leap second at the end
5265  of June 2007.
5266
5267
5268Release 2007a - 2007-01-08 12:28:29 -0500
5269
5270  changes by Paul Eggert
5271
5272  Derick Rethans's Asmara change
5273
5274  Oscar van Vlijmen's Easter Island local mean time change
5275
5276  symbolic link changes
5277
5278
5279Release 2006p - 2006-11-27 08:54:27 -0500
5280
5281  changes by Paul Eggert
5282
5283
5284Release 2006o - 2006-11-06 09:18:07 -0500
5285
5286  changes by Paul Eggert
5287
5288
5289Release 2006n - 2006-10-10 11:32:06 -0400
5290
5291  changes by Paul Eggert
5292
5293
5294Release 2006m - 2006-10-02 15:32:35 -0400
5295
5296  changes for Uruguay, Palestine, and Egypt by Paul Eggert
5297
5298  (minimalist) changes to zic.8 to clarify "until" information
5299
5300
5301Release data2006l - 2006-09-18 12:58:11 -0400
5302
5303  Paul's best-effort work on this coming weekend's Egypt time change
5304
5305
5306Release 2006k - 2006-08-28 12:19:09 -0400
5307
5308  changes by Paul Eggert
5309
5310
5311Release 2006j - 2006-08-21 09:56:32 -0400
5312
5313  changes by Paul Eggert
5314
5315
5316Release code2006i - 2006-08-07 12:30:55 -0400
5317
5318  localtime.c fixes
5319
5320  Ken Pizzini's conversion script
5321
5322
5323Release code2006h - 2006-07-24 09:19:37 -0400
5324
5325  adds public domain notices to four files
5326
5327  includes a fix for transition times being off by a second
5328
5329  adds a new recording to the "arts" file (information courtesy Colin Bowern)
5330
5331
5332Release 2006g - 2006-05-08 17:18:09 -0400
5333
5334  northamerica changes by Paul Eggert
5335
5336
5337Release 2006f - 2006-05-01 11:46:00 -0400
5338
5339  a missing version number problem is fixed (with thanks to Bradley
5340  White for catching the problem)
5341
5342
5343Release 2006d - 2006-04-17 14:33:43 -0400
5344
5345  changes by Paul Eggert
5346
5347  added new items to tz-arts.htm that were found by Paul
5348
5349
5350Release 2006c - 2006-04-03 10:09:32 -0400
5351
5352  two sets of data changes by Paul Eggert
5353
5354  a fencepost error fix in zic.c
5355
5356  changes to zic.c and the "europe" file to minimize differences
5357  between output produced by the old 32-bit zic and the new 64-bit
5358  version
5359
5360
5361Release 2006b - 2006-02-20 10:08:18 -0500
5362  [tz32code2006b + tz64code2006b + tzdata2006b]
5363
5364  64-bit code
5365
5366  All SCCS IDs were bumped to "8.1" for this release.
5367
5368
5369Release 2006a - 2006-01-30 08:59:31 -0500
5370
5371  changes by Paul Eggert (in particular, Indiana time zone moves)
5372
5373  an addition to the zic manual page to describe how special-case
5374  transitions are handled
5375
5376
5377Release 2005r - 2005-12-27 09:27:13 -0500
5378
5379  Canadian changes by Paul Eggert
5380
5381  They also add "<pre>" directives to time zone data files and reflect
5382  changes to warning message logic in "zdump.c" (but with calls to
5383  "gettext" kept unbundled at the suggestion of Ken Pizzini).
5384
5385
5386Release 2005q - 2005-12-13 09:17:09 -0500
5387
5388  Nothing earth-shaking here:
5389	1.  Electronic mail addresses have been removed.
5390	2.  Casts of the return value of exit have been removed.
5391	3.  Casts of the argument of is.* macros have been added.
5392	4.  Indentation in one section of zic.c has been fixed.
5393	5.  References to dead URLs in the data files have been dealt with.
5394
5395
5396Release 2005p - 2005-12-05 10:30:53 -0500
5397
5398  "systemv", "tz-link.htm", and "zdump.c" changes
5399  (less the casts of arguments to the is* macros)
5400
5401
5402Release 2005o - 2005-11-28 10:55:26 -0500
5403
5404  Georgia, Cuba, Nicaragua, and Jordan changes by Paul Eggert
5405
5406  zdump.c lint fixes by Arthur David Olson
5407
5408
5409Release 2005n - 2005-10-03 09:44:09 -0400
5410
5411  changes by Paul Eggert (both the Uruguay changes and the Kyrgyzstan
5412  et al. changes)
5413
5414
5415Release 2005m - 2005-08-29 12:15:40 -0400
5416
5417  changes by Paul Eggert (with a small tweak to the tz-art change)
5418
5419  a declaration of an unused variable has been removed from zdump.c
5420
5421
5422Release 2005l - 2005-08-22 12:06:39 -0400
5423
5424  changes by Paul Eggert
5425
5426  overflow/underflow checks by Arthur David Olson, minus changes to
5427  the "Theory" file about the pending addition of 64-bit data (I grow
5428  less confident of the changes being accepted with each passing day,
5429  and the changes no longer increase the data files nine-fold--there's
5430  less than a doubling in size by my local Sun's reckoning)
5431
5432
5433Release 2005k - 2005-07-14 14:14:24 -0400
5434
5435  The "leapseconds" file has been edited to reflect the recently
5436  announced leap second at the end of 2005.
5437
5438  I've also deleted electronic mail addresses from the files as an
5439  anti-spam measure.
5440
5441
5442Release 2005j - 2005-06-13 14:34:13 -0400
5443
5444  These reflect changes to limit the length of time zone abbreviations
5445  and the characters used in those abbreviations.
5446
5447  There are also changes to handle POSIX-style "quoted" timezone
5448  environment variables.
5449
5450  The changes were circulated on the time zone mailing list; the only
5451  change since then was the removal of a couple of minimum-length of
5452  abbreviation checks.
5453
5454
5455Release data2005i - 2005-04-21 15:04:16 -0400
5456
5457  changes (most importantly to Nicaragua and Haiti) by Paul Eggert
5458
5459
5460Release 2005h - 2005-04-04 11:24:47 -0400
5461
5462  changes by Paul Eggert
5463
5464  minor changes to Makefile and zdump.c to produce more useful output
5465  when doing a "make typecheck"
5466
5467
5468Release 2005g - 2005-03-14 10:11:21 -0500
5469
5470  changes by Paul Eggert (a change to current DST rules in Uruguay and
5471  an update to a link to time zone software)
5472
5473
5474Release 2005f - 2005-03-01 08:45:32 -0500
5475
5476  data and documentation changes by Paul Eggert
5477
5478
5479Release 2005e - 2005-02-10 15:59:44 -0500
5480
5481  [not summarized]
5482
5483
5484Release code2005d - 2005-01-31 09:21:47 -0500
5485
5486  make zic complain about links to links if the -v flag is used
5487
5488  have "make public" do more code checking
5489
5490  add an include to "localtime.c" for the benefit of gcc systems
5491
5492
5493Release 2005c - 2005-01-17 18:36:29 -0500
5494
5495  get better results when mktime runs on a system where time_t is double
5496
5497  changes to the data files (most importantly to Paraguay)
5498
5499
5500Release 2005b - 2005-01-10 09:19:54 -0500
5501
5502  Get localtime and gmtime working on systems with exotic time_t types.
5503
5504  Update the leap second commentary in the "leapseconds" file.
5505
5506
5507Release 2005a - 2005-01-01 13:13:44 -0500
5508
5509  [not summarized]
5510
5511
5512Release code2004i - 2004-12-14 13:42:58 -0500
5513
5514  Deal with systems where time_t is unsigned.
5515
5516
5517Release code2004h - 2004-12-07 11:40:18 -0500
5518
5519  64-bit-time_t changes
5520
5521
5522Release 2004g - 2004-11-02 09:06:01 -0500
5523
5524  update to Cuba (taking effect this weekend)
5525
5526  other changes by Paul Eggert
5527
5528  correction of the spelling of Oslo
5529
5530  changed versions of difftime.c and private.h
5531
5532
5533Release code2004f - 2004-10-21 10:25:22 -0400
5534
5535  Cope with wide-ranging tm_year values.
5536
5537
5538Release 2004e - 2004-10-11 14:47:21 -0400
5539
5540  Brazil/Argentina/Israel changes by Paul Eggert
5541
5542  changes to tz-link.htm by Paul
5543
5544  one small fix to Makefile
5545
5546
5547Release 2004d - 2004-09-22 08:27:29 -0400
5548
5549  Avoid overflow problems when TM_YEAR_BASE is added to an integer.
5550
5551
5552Release 2004c - 2004-08-11 12:06:26 -0400
5553
5554  asctime-related changes
5555
5556  (variants of) some of the documentation changes suggested by Paul Eggert
5557
5558
5559Release 2004b - 2004-07-19 14:33:35 -0400
5560
5561  data changes by Paul Eggert - most importantly, updates for Argentina
5562
5563
5564Release 2004a - 2004-05-27 12:00:47 -0400
5565
5566  changes by Paul Eggert
5567
5568  Handle DST transitions that occur at the end of a month in some
5569  years but at the start of the following month in other years.
5570
5571  Add a copy of the correspondence that's the basis for claims about
5572  DST in the Navajo Nation.
5573
5574
5575Release 2003e - 2003-12-15 09:36:47 -0500
5576
5577  changes by Arthur David Olson (primarily code changes)
5578
5579  changes by Paul Eggert (primarily data changes)
5580
5581  minor changes to "Makefile" and "northamerica" (in the latter case,
5582  optimization of the "Toronto" rules)
5583
5584
5585Release 2003d - 2003-10-06 09:34:44 -0400
5586
5587  changes by Paul Eggert
5588
5589
5590Release 2003c - 2003-09-16 10:47:05 -0400
5591
5592  Fix bad returns in zic.c's inleap function.
5593  Thanks to Bradley White for catching the problem!
5594
5595
5596Release 2003b - 2003-09-16 07:13:44 -0400
5597
5598  Add a "--version" option (and documentation) to the zic and zdump commands.
5599
5600  changes to overflow/underflow checking in zic
5601
5602  a localtime typo fix.
5603
5604  Update the leapseconds and tz-art.htm files.
5605
5606
5607Release 2003a - 2003-03-24 09:30:54 -0500
5608
5609  changes by Paul Eggert
5610
5611  a few additions and modifications to the tz-art.htm file
5612
5613
5614Release 2002d - 2002-10-15 13:12:42 -0400
5615
5616  changes by Paul Eggert, less the "Britain (UK)" change in iso3166.tab
5617
5618  There's also a new time zone quote in "tz-art.htm".
5619
5620
5621Release 2002c - 2002-04-04 11:55:20 -0500
5622
5623  changes by Paul Eggert
5624
5625  Change zic.c to avoid creating symlinks to files that don't exist.
5626
5627
5628Release 2002b - 2002-01-28 12:56:03 -0500
5629
5630  [These change notes are for Release 2002a, which was corrupted.
5631  2002b was a corrected version of 2002a.]
5632
5633  changes by Paul Eggert
5634
5635  Update the "leapseconds" file to note that there'll be no leap
5636  second at the end of June, 2002.
5637
5638  Change "zic.c" to deal with a problem in handling the "Asia/Bishkek" zone.
5639
5640  Change to "difftime.c" to avoid sizeof problems.
5641
5642
5643Release 2001d - 2001-10-09 13:31:32 -0400
5644
5645  changes by Paul Eggert
5646
5647
5648Release 2001c - 2001-06-05 13:59:55 -0400
5649
5650  changes by Paul Eggert and Andrew Brown
5651
5652
5653Release 2001b - 2001-04-05 16:44:38 -0400
5654
5655  changes by Paul Eggert (modulo jnorgard's typo fix)
5656
5657  tz-art.htm has been HTMLified.
5658
5659
5660Release 2001a - 2001-03-13 12:57:44 -0500
5661
5662  changes by Paul Eggert
5663
5664  An addition to the "leapseconds" file: comments with the text of the
5665  latest IERS leap second notice.
5666
5667  Trailing white space has been removed from data file lines, and
5668  repeated spaces in "Rule Jordan" lines in the "asia" file have been
5669  converted to tabs.
5670
5671
5672Release 2000h - 2000-12-14 15:33:38 -0500
5673
5674  changes by Paul Eggert
5675
5676  one typo fix in the "art" file
5677
5678  With providence, this is the last update of the millennium.
5679
5680
5681Release 2000g - 2000-10-10 11:35:22 -0400
5682
5683  changes by Paul Eggert
5684
5685  correction of John Mackin's name submitted by Robert Elz
5686
5687  Garry Shandling's Daylight Saving Time joke (!?!) from the recent
5688  Emmy Awards broadcast.
5689
5690
5691Release 2000f - 2000-08-10 09:31:58 -0400
5692
5693  changes by Paul Eggert
5694
5695  Added information in "tz-art.htm" on a Seinfeld reference to DST.
5696
5697  Error checking and messages in the "yearistype" script have been
5698  improved.
5699
5700
5701Release 2000e - 2000-07-31 09:27:54 -0400
5702
5703  data changes by Paul Eggert
5704
5705  a change to the default value of the defined constant HAVE_STRERROR
5706
5707  the addition of a Dave Barry quote on DST to the tz-arts file
5708
5709
5710Release 2000d - 2000-04-20 15:43:04 -0400
5711
5712  changes to the documentation and code of strftime for C99 conformance
5713
5714  a bug fix for date.c
5715
5716  These are based on (though modified from) changes by Paul Eggert.
5717
5718
5719Release 2000c - 2000-03-04 10:31:43 -0500
5720
5721  changes by Paul Eggert
5722
5723
5724Release 2000b - 2000-02-21 12:16:29 -0500
5725
5726  changes by Paul Eggert and Joseph Myers
5727
5728  modest tweaks to the tz-art.htm and tz-link.htm files
5729
5730
5731Release 2000a - 2000-01-18 09:21:26 -0500
5732
5733  changes by Paul Eggert
5734
5735  The two hypertext documents have also been renamed.
5736
5737
5738Release code1999i-data1999j - 1999-11-15 18:43:22 -0500
5739
5740  Paul Eggert's changes
5741
5742  additions to the "zic" manual page and the "Arts.htm" file
5743
5744
5745Release code1999h-data1999i - 1999-11-08 14:55:21 -0500
5746
5747  [not summarized]
5748
5749
5750Release data1999h - 1999-10-07 03:50:29 -0400
5751
5752  changes by Paul Eggert to "europe" (most importantly, fixing
5753  Lithuania and Estonia)
5754
5755
5756Release 1999g - 1999-09-28 11:06:18 -0400
5757
5758  data changes by Paul Eggert (most importantly, the change for
5759  Lebanon that buys correctness for this coming Sunday)
5760
5761  The "code" file contains changes to "Makefile" and "checktab.awk" to
5762  allow better checking of time zone files before they are published.
5763
5764
5765Release 1999f - 1999-09-23 09:48:14 -0400
5766
5767  changes by Arthur David Olson and Paul Eggert
5768
5769
5770Release 1999e - 1999-08-17 15:20:54 -0400
5771
5772  changes circulated by Paul Eggert, although the change to handling
5773  of DST-specifying timezone names has been commented out for now
5774  (search for "XXX" in "localtime.c" for details).  These files also
5775  do not make any changes to the start of DST in Brazil.
5776
5777  In addition to Paul's changes, there are updates to "Arts.htm" and
5778  cleanups of URLs.
5779
5780
5781Release 1999d - 1999-03-30 11:31:07 -0500
5782
5783  changes by Paul Eggert
5784
5785  The Makefile's "make public" rule has also been changed to do a test
5786  compile of each individual time zone data file (which should help
5787  avoid problems such as the one we had with Nicosia).
5788
5789
5790Release 1999c - 1999-03-25 09:47:47 -0500
5791
5792  changes by Paul Eggert, most importantly the change for Chile.
5793
5794
5795Release 1999b - 1999-02-01 17:51:44 -0500
5796
5797  changes by Paul Eggert
5798
5799  code changes (suggested by Mani Varadarajan, mani at be.com) for
5800  correct handling of symbolic links when building using a relative directory
5801
5802  code changes to generate correct messages for failed links
5803
5804  updates to the URLs in Arts.htm
5805
5806
5807Release 1999a - 1999-01-19 16:20:29 -0500
5808
5809  error message internationalizations and corrections in zic.c and
5810  zdump.c (as suggested by Vladimir Michl, vladimir.michl at upol.cz,
5811  to whom thanks!)
5812
5813
5814Release code1998h-data1998i - 1998-10-01 09:56:10 -0400
5815
5816  changes for Brazil, Chile, and Germany
5817
5818  support for use of "24:00" in the input files for the time zone compiler
5819
5820
5821Release code1998g-data1998h - 1998-09-24 10:50:28 -0400
5822
5823  changes by Paul Eggert
5824
5825  correction to a define in the "private.h" file
5826
5827
5828Release data1998g - 1998-08-11 03:28:35 -0000
5829  [tzdata1998g.tar.gz is missing!]
5830
5831  Lithuanian change provided by mgedmin at pub.osf.it
5832
5833  Move creation of the GMT link with Etc/GMT to "etcetera" (from
5834  "backward") to ensure that the GMT file is created even where folks
5835  don't want the "backward" links (as suggested by Paul Eggert).
5836
5837
5838Release data1998f - 1998-07-20 13:50:00 -0000
5839  [tzdata1998f.tar.gz is missing!]
5840
5841  Update the "leapseconds" file to include the newly announced
5842  insertion at the end of 1998.
5843
5844
5845Release code1998f - 1998-06-01 10:18:31 -0400
5846
5847  addition to localtime.c by Guy Harris
5848
5849
5850Release 1998e - 1998-05-28 09:56:26 -0400
5851
5852  The Makefile is changed to produce zoneinfo-posix rather than
5853  zoneinfo/posix, and to produce zoneinfo-leaps rather than
5854  zoneinfo/right.
5855
5856  data changes by Paul Eggert
5857
5858  changes from Guy Harris to provide asctime_r and ctime_r
5859
5860  A usno1998 file (substantially identical to usno1997) has been added.
5861
5862
5863Release 1998d - 1998-05-14 11:58:34 -0400
5864
5865  changes to comments (in particular, elimination of references to CIA maps).
5866  "Arts.htm", "WWW.htm", "asia", and "australasia" are the only places
5867  where changes occur.
5868
5869
5870Release 1998c - 1998-02-28 12:32:26 -0500
5871
5872  changes by Paul Eggert (save the "French correction," on which I'll
5873  wait for the dust to settle)
5874
5875  symlink changes
5876
5877  changes and additions to Arts.htm
5878
5879
5880Release 1998b - 1998-01-17 14:31:51 -0500
5881
5882  URL cleanups and additions
5883
5884
5885Release 1998a - 1998-01-13 12:37:35 -0500
5886
5887  changes by Paul Eggert
5888
5889
5890Release code1997i-data1997k - 1997-12-29 09:53:41 -0500
5891
5892  changes by Paul Eggert, with minor modifications from Arthur David
5893  Olson to make the files more browser friendly
5894
5895
5896Release code1997h-data1997j - 1997-12-18 17:47:35 -0500
5897
5898  minor changes to put "TZif" at the start of each timezone information file
5899
5900  a rule has also been added to the Makefile so you can
5901	make zones
5902  to just recompile the zone information files (rather than doing a
5903  full "make install" with its other effects).
5904
5905
5906Release data1997i - 1997-10-07 08:45:38 -0400
5907
5908  changes to Africa by Paul Eggert
5909
5910
5911Release code1997g-data1997h - 1997-09-04 16:56:54 -0400
5912
5913  corrections for Uruguay (and other locations)
5914
5915  Arthur David Olson's simple-minded fix allowing mktime to both
5916  correctly handle leap seconds and correctly handle tm_sec values
5917  upon which arithmetic has been performed.
5918
5919
5920Release code1997f-data1997g - 1997-07-19 13:15:02 -0400
5921
5922  Paul Eggert's updates
5923
5924  a small change to a function prototype;
5925
5926  "Music" has been renamed "Arts.htm", HTMLified, and augmented to
5927  include information on Around the World in Eighty Days.
5928
5929
5930Release code1997e-data1997f - 1997-05-03 18:52:34 -0400
5931
5932  fixes to zic's error handling
5933
5934  changes inspired by the item circulated on Slovenia
5935
5936  The description of Web resources has been HTMLified for browsing
5937  convenience.
5938
5939  A new piece of tz-related music has been added to the "Music" file.
5940
5941
5942Release code1997d-data1997e - 1997-03-29 12:48:52 -0500
5943
5944  Paul Eggert's latest suggestions
5945
5946
5947Release code1997c-data1997d - 1997-03-07 20:37:54 -0500
5948
5949  changes to "zic.c" to correct performance of the "-s" option
5950
5951  a new file "usno1997"
5952
5953
5954Release data1997c - 1997-03-04 09:58:18 -0500
5955
5956  changes in Israel
5957
5958
5959Release 1997b - 1997-02-27 18:34:19 -0500
5960
5961  The data file incorporates the 1997 leap second.
5962
5963  The code file incorporates Arthur David Olson's take on the
5964  zic/multiprocessor/directory-creation situation.
5965
5966
5967Release 1997a - 1997-01-21 09:11:10 -0500
5968
5969  Paul Eggert's Antarctica (and other changes)
5970
5971  Arthur David Olson finessed the "getopt" issue by checking against
5972  both -1 and EOF (regardless of POSIX, SunOS 4.1.1's manual says -1
5973  is returned while SunOS 5.5's manual says EOF is returned).
5974
5975
5976Release code1996o-data1996n - 1996-12-27 21:42:05 -0500
5977
5978  Paul Eggert's latest changes
5979
5980
5981Release code1996n - 1996-12-16 09:42:02 -0500
5982
5983  link snapping fix from Bruce Evans (via Garrett Wollman)
5984
5985
5986Release data1996m - 1996-11-24 02:37:34 -0000
5987  [tzdata1996m.tar.gz is missing!]
5988
5989  Paul Eggert's batch of changes
5990
5991
5992Release code1996m-data1996l - 1996-11-05 14:00:12 -0500
5993
5994  No functional changes here; the files have simply been changed to
5995  make more use of ISO style dates in comments. The names of the above
5996  files now include the year in full.
5997
5998
5999Release code96l - 1996-09-08 17:12:20 -0400
6000
6001  tzcode96k was missing a couple of pieces.
6002
6003
6004Release 96k - 1996-09-08 16:06:22 -0400
6005
6006  the latest round of changes from Paul Eggert
6007
6008  the recent Year 2000 material
6009
6010
6011Release code96j - 1996-07-30 13:18:53 -0400
6012
6013  Set sp->typecnt as suggested by Timothy Patrick Murphy.
6014
6015
6016Release code96i - 1996-07-27 20:11:35 -0400
6017
6018  Paul's suggested patch for strftime %V week numbers
6019
6020
6021Release data96i - 1996-07-01 18:13:04 -0400
6022
6023  "northamerica" and "europe" changes by Paul Eggert
6024
6025
6026Release code96h - 1996-06-05 08:02:21 -0400
6027
6028  fix for handling transitions specified in Universal Time
6029
6030  Some "public domain" notices have also been added.
6031
6032
6033Release code96g - 1996-05-16 14:00:26 -0400
6034
6035  fix for the simultaneous-DST-and-zone-change challenge
6036
6037
6038Release data96h - 1996-05-09 17:40:51 -0400
6039
6040  changes by Paul Eggert
6041
6042
6043Release code96f-data96g - 1996-05-03 03:09:59 -0000
6044  [tzcode96f.tar.gz + tzdata96g.tar.gz are both missing!]
6045
6046  The changes get us some of the way to fixing the problems noted in Paul
6047  Eggert's letter yesterday (in addition to a few others).  The approach
6048  has been to make zic a bit smarter about figuring out what time zone
6049  abbreviations apply just after the time specified in the "UNTIL" part
6050  of a zone line.  Putting the smarts in zic means avoiding having
6051  transition times show up in both "Zone" lines and "Rule" lines, which
6052  in turn avoids multiple transition time entries in time zone files.
6053  (This also makes the zic input files such as "europe" a bit shorter and
6054  should ease maintenance.)
6055
6056
6057Release data96f - 1996-04-19 19:20:03 -0000
6058  [tzdata96f.tar.gz is missing!]
6059
6060  The only changes are to the "northamerica" file; the time zone
6061  abbreviation for Denver is corrected to MST (and MDT), and the
6062  comments for Mexico have been updated.
6063
6064
6065Release data96e - 1996-03-19 17:37:26 -0500
6066
6067  Proposals by Paul Eggert, in particular the Portugal change that
6068  comes into play at the end of this month.
6069
6070
6071Release data96d - 1996-03-18 20:49:39 -0500
6072
6073  [not summarized]
6074
6075
6076Release code96e - 1996-02-29 15:43:27 -0000
6077  [tzcode96e.tar.gz is missing!]
6078
6079  internationalization changes and the fix to the documentation for strftime
6080
6081
6082Release code96d-data96c - 1996-02-12 11:05:27 -0500
6083
6084  The "code" file simply updates Bob Kridle's electronic address.
6085
6086  The "data" file updates rules for Mexico.
6087
6088
6089Release data96b - 1996-01-27 15:44:42 -0500
6090
6091  Kiribati change
6092
6093
6094Release code96c - 1996-01-16 16:58:15 -0500
6095
6096  leap-year streamlining and binary-search changes
6097
6098  fix to newctime.3
6099
6100
6101Release code96b - 1996-01-10 20:42:39 -0500
6102
6103  fixes and enhancements from Paul Eggert, including code that
6104  emulates the behavior of recent versions of the SunOS "date"
6105  command.
6106
6107
6108Release 96a - 1996-01-06 09:08:24 -0500
6109
6110  Israel updates
6111
6112  fixes to strftime.c for correct ISO 8601 week number generation,
6113  plus support for two new formats ('G' and 'g') to give ISO 8601 year
6114  numbers (which are not necessarily the same as calendar year numbers)
6115
6116
6117Release code95i-data95m - 1995-12-21 12:46:47 -0500
6118
6119  The latest revisions from Paul Eggert are included, the usno1995
6120  file has been updated, and a new file ("WWW") covering useful URLs
6121  has been added.
6122
6123
6124Release code95h-data95l - 1995-12-19 18:10:12 -0500
6125
6126  A simplification of a macro definition, a change to data for Sudan,
6127  and (for last minute shoppers) notes in the "Music" file on the CD
6128  "Old Man Time".
6129
6130
6131Release code95g-data95k - 1995-10-30 10:32:47 -0500
6132
6133  (slightly reformatted) 8-bit-clean proposed patch
6134
6135  minor patch: US/Eastern -> America/New_York
6136
6137  snapshot of the USNO's latest data ("usno1995")
6138
6139  some other minor cleanups
6140
6141
6142Release code95f-data95j - 1995-10-28 21:01:34 -0000
6143  [tzcode95f.tar.gz + tzdata95j.tar.gz are both missing!]
6144
6145  European cleanups
6146
6147  support for 64-bit time_t's
6148
6149  optimization in localtime.c
6150
6151
6152Release code95e - 1995-10-13 13:23:57 -0400
6153
6154  the mktime change to scan from future to past when trying to find time zone
6155  offsets
6156
6157
6158Release data95i - 1995-09-26 10:43:26 -0400
6159
6160  For Canada/Central, guess that the Sun customer's "one week too
6161  early" was just a approximation, and the true error is one month
6162  too early.  This is consistent with the rest of Canada.
6163
6164
6165Release data95h - 1995-09-21 11:26:48 -0400
6166
6167  latest changes from Paul Eggert
6168
6169
6170Release code95d - 1995-09-14 11:14:45 -0400
6171
6172  the addition of a "Music" file, which documents four recorded
6173  versions of the tune "Save That Time".
6174
6175
6176Release data95g - 1995-09-01 17:21:36 -0400
6177
6178  "yearistype" correction
6179
6180
6181Release data95f - 1995-08-28 20:46:56 -0400
6182
6183  Paul Eggert's change to the australasia file
6184
6185
6186Release data95e - 1995-07-08 18:02:34 -0400
6187
6188  The only change is a leap second at the end of this year.
6189  Thanks to Bradley White for forwarding news on the leap second.
6190
6191
6192Release data95d - 1995-07-03 13:26:22 -0400
6193
6194  Paul Eggert's changes
6195
6196
6197Release data95c - 1995-07-02 19:19:28 -0400
6198
6199  changes to "asia", "backward", "europe", and "southamerica"
6200  (read: northamericacentrics need not apply)
6201
6202
6203Release code95c - 1995-03-13 14:00:46 -0500
6204
6205  one-line fix for sign extension problems in detzcode
6206
6207
6208Release 95b - 1995-03-04 11:22:38 -0500
6209
6210  Minor changes in both:
6211
6212  The "code" file contains a workaround for the lack of "unistd.h" in
6213  Microsoft C++ version 7.
6214
6215  The "data" file contains a fixed "Link" for America/Shiprock.
6216
6217
6218Release 94h - 1994-12-10 12:51:14 -0500
6219
6220  The files:
6221
6222  *	incorporate the changes to "zdump" and "date" to make changes to
6223	the "TZ" environment variable permanent;
6224
6225  *	incorporate the table changes by Paul Eggert;
6226
6227  *	include (and document) support for universal time specifications in
6228	data files - but do not (yet) include use of this feature in the
6229	data files.
6230
6231  Think of this as "TZ Classic" - the software has been set up not to break if
6232  universal time shows up in its input, and data entries have been
6233  left as is so as not to break existing implementations.
6234
6235
6236Release data94f - 1994-08-20 12:56:09 -0400
6237
6238  (with thanks!) the latest data updates from Paul Eggert
6239
6240
6241Release data94e - 1994-06-04 13:13:53 -0400
6242
6243  [not summarized]
6244
6245
6246Release code94g - 1994-05-05 12:14:07 -0400
6247
6248  fix missing "optind.c" and a reference to it in the Makefile
6249
6250
6251Release code94f - 1994-05-05 13:00:33 -0000
6252  [tzcode94f.tar.gz is missing!]
6253
6254  changes to avoid overflow in difftime, as well as changes to cope
6255  with the 52/53 challenge in strftime
6256
6257
6258Release code94e - 1994-03-30 23:32:59 -0500
6259
6260  change for the benefit of PCTS
6261
6262
6263Release 94d - 1994-02-24 15:42:25 -0500
6264
6265  Avoid clashes with POSIX semantics for zones such as GMT+4.
6266
6267  Some other very minor housekeeping is also present.
6268
6269
6270Release code94c - 1994-02-10 08:52:40 -0500
6271
6272  Fix bug where mkdirs was broken unless you compile with
6273  -fwritable-strings (which is generally losing to do).
6274
6275
6276Release 94b - 1994-02-07 10:04:33 -0500
6277
6278  work by Paul Eggert who notes:
6279
6280  I found another book of time zone histories by E W Whitman; it's not
6281  as extensive as Shanks but has a few goodies of its own.  I used it
6282  to update the tables.  I also fixed some more as a result of
6283  correspondence with Adam David and Peter Ilieve, and move some stray
6284  links from 'europe' to 'backward'.  I corrected some scanning errors
6285  in usno1989.
6286
6287  As far as the code goes, I fixed zic to allow years in the range
6288  INT_MIN to INT_MAX; this fixed a few boundary conditions around 1900.
6289  And I cleaned up the zic documentation a little bit.
6290
6291
6292Release data94a - 1994-02-03 08:58:54 -0500
6293
6294  It simply incorporates the recently announced leap second into the
6295  "leapseconds" file.
6296
6297
6298Release 93g - 1993-11-22 17:28:27 -0500
6299
6300  Paul Eggert has provided a good deal of historic information (based
6301  on Shanks), and there are some code changes to deal with the buglets
6302  that crawled out in dealing with the new information.
6303
6304
6305Release 93f - 1993-10-15 12:27:46 -0400
6306
6307  Paul Eggert's changes
6308
6309
6310Release 93e - 1993-09-05 21:21:44 -0400
6311
6312  This has updated data for Israel, England, and Kwajalein.  There's
6313  also an update to "zdump" to cope with Kwajalein's 24-hour jump.
6314  Thanks to Paul Eggert and Peter Ilieve for the changes.
6315
6316
6317Release 93d - 1993-06-17 23:34:17 -0400
6318
6319  new fix and new data on Israel
6320
6321
6322Release 93c - 1993-06-06 19:31:55 -0400
6323
6324  [not summarized]
6325
6326
6327Release 93b - 1993-02-02 14:53:58 -0500
6328
6329  updated "leapseconds" file
6330
6331
6332Release 93 - 1993-01-08 07:01:06 -0500
6333
6334  At kre's suggestion, the package has been split in two - a code piece
6335  (which also includes documentation) that's only of use to folks who
6336  want to recompile things and a data piece useful to anyone who can
6337  run "zic".
6338
6339  The new version has a few changes to the data files, a few
6340  portability changes, and an off-by-one fix (with thanks to
6341  Tom Karzes at deshaw.com for providing a description and a
6342  solution).
6343
6344
6345Release 92c - 1992-11-21 17:35:36 -0000
6346  [tz92c.tar.Z is missing!]
6347
6348  The fallout from the latest round of DST transitions.
6349
6350  There are changes for Portugal, Saskatchewan, and "Pacific-New";
6351  there's also a change to "zic.c" that makes it portable to more systems.
6352
6353
6354Release 92 - 1992-04-25 18:17:03 -0000
6355  [tz92.tar.Z is missing!]
6356
6357  By popular demand (well, at any rate, following a request by kre at munnari)
6358
6359
6360The 1989 update of the time zone package featured:
6361
6362  *	POSIXization (including interpretation of POSIX-style TZ environment
6363	variables, provided by Guy Harris),
6364  *	ANSIfication (including versions of "mktime" and "difftime"),
6365  *	SVIDulation (an "altzone" variable)
6366  *	MACHination (the "gtime" function)
6367  *	corrections to some time zone data (including corrections to the rules
6368	for Great Britain and New Zealand)
6369  *	reference data from the United States Naval Observatory for folks who
6370	want to do additional time zones
6371  *	and the 1989 data for Saudi Arabia.
6372
6373  (Since this code will be treated as "part of the implementation" in some
6374  places and as "part of the application" in others, there's no good way to
6375  name functions, such as timegm, that are not part of the proposed ANSI C
6376  standard; such functions have kept their old, underscore-free names in this
6377  update.)
6378
6379  And the "dysize" function has disappeared; it was present to allow
6380  compilation of the "date" command on old BSD systems, and a version of "date"
6381  is now provided in the package.  The "date" command is not created when you
6382  "make all" since it may lack options provided by the version distributed with
6383  your operating system, or may not interact with the system in the same way
6384  the native version does.
6385
6386  Since POSIX frowns on correct leap second handling, the default behavior of
6387  the "zic" command (in the absence of a "-L" option) has been changed to omit
6388  leap second information from its output files.
6389
6390
6391-----
6392Notes
6393
6394This file contains copies of the part of each release announcement
6395that talks about the changes in that release.  The text has been
6396adapted and reformatted for the purposes of this file.
6397
6398Traditionally a release R consists of a pair of tarball files,
6399tzcodeR.tar.gz and tzdataR.tar.gz.  However, some releases (e.g.,
6400code2010a, data2012c) consist of just one or the other tarball, and a
6401few (e.g., code2012c-data2012d) have tarballs with mixed version
6402numbers.  Recent releases also come in an experimental format
6403consisting of a single tarball tzdb-R.tar.lz with extra data.
6404
6405Release timestamps are taken from the release's commit (for newer,
6406Git-based releases), from the newest file in the tarball (for older
6407releases, where this info is available) or from the email announcing
6408the release (if all else fails; these are marked with a time zone
6409abbreviation of -0000 and an "is missing!" comment).
6410
6411Earlier versions of the code and data were not announced on the tz
6412list and are not summarized here.
6413
6414This file is in the public domain.
6415
6416Local Variables:
6417coding: utf-8
6418End:
6419