2023.1: Release of upstream tzdata 2023a

Version 2023.1

Upstream version 2023a released 2023-03-22T19:39:33+00:00

Briefly:

Egypt now uses DST again, from April through October. This year Morocco springs
forward April 23, not April 30. Palestine delays the start of DST this year.
Much of Greenland still uses DST from 2024 on. America/Yellowknife now links to
America/Edmonton. tzselect can now use current time to help infer timezone. The
code now defaults to C99 or later. Fix use of C23 attributes.

Changes to future timestamps

Starting in 2023, Egypt will observe DST from April's last Friday through
October's last Thursday. (Thanks to Ahmad ElDardiry.) Assume the transition
times are 00:00 and 24:00, respectively.

In 2023 Morocco's spring-forward transition after Ramadan will occur April 23,
not April 30. (Thanks to Milamber.) Adjust predictions for future years
accordingly. This affects predictions for 2023, 2031, 2038, and later years.

This year Palestine will delay its spring forward from March 25 to April 29 due
to Ramadan. (Thanks to Heba Hamad.) Make guesses for future Ramadans too.

Much of Greenland, represented by America/Nuuk, will continue to observe DST
using European Union rules. When combined with Greenland's decision not to
change the clocks in fall 2023, America/Nuuk therefore changes from -03/-02 to
-02/-01 effective 2023-10-29 at 01:00 UTC. (Thanks to Thomas M. Steenholdt.)
This change from 2022g doesn't affect timestamps until 2024-03-30, and doesn't
affect tm_isdst until 2023-03-25.

Changes to past timestamps

America/Yellowknife has changed from a Zone to a backward compatibility Link, as
it no longer differs from America/Edmonton since 1970. (Thanks to Almaz
Mingaleev.) This affects some pre-1948 timestamps. The old data are now in
'backzone'.

Changes to past time zone abbreviations

When observing Moscow time, Europe/Kirov and Europe/Volgograd now use the
abbreviations MSK/MSD instead of numeric abbreviations, for consistency with
other timezones observing Moscow time.

Changes to commentary

tz-link.html has a new section "Coordinating with governments and distributors".
(Thanks to Neil Fuller for some of the text.)

To improve tzselect diagnostics, zone1970.tab's comments column is now limited
to countries that have multiple timezones.

Note that leap seconds are planned to be discontinued by 2035.

2022.7: Release of upstream tzdata 2022g

Version 2022.7

Upstream version 2022g released 2022-11-29T16:58:31+00:00

Briefly:

The northern edge of Chihuahua changes to US timekeeping. Much of Greenland
stops changing clocks after March 2023. Fix some pre-1996 timestamps in northern
Canada. C89 is now deprecated; please use C99 or later. Portability fixes for
AIX, libintl, MS-Windows, musl, z/OS In C code, use more C23 features if
available. C23 timegm now supported by default Fixes for unlikely integer
overflows

Changes to future timestamps

In the Mexican state of Chihuahua, the border strip near the US will change to
agree with nearby US locations on 2022-11-30. The strip's western part,
represented by Ciudad Juárez, switches from -06 all year to -07/-06 with US DST
rules, like El Paso, TX. The eastern part, represented by Ojinaga, will observe
US DST next year, like Presidio, TX. (Thanks to Heitor David Pinto.) A new Zone
America/Ciudad_Juarez splits from America/Ojinaga.

Much of Greenland, represented by America/Nuuk, stops observing winter time
after March 2023, so its daylight saving time becomes standard time. (Thanks to
Jonas Nyrup and Jürgen Appel.)

Changes to past timestamps

Changes for pre-1996 northern Canada (thanks to Chris Walton):

Merge America/Iqaluit and America/Pangnirtung into the former, with a backward
compatibility link for the latter name. There is no good evidence the two
locations differ since 1970. This change affects pre-1996 America/Pangnirtung
timestamps.

Cambridge Bay, Inuvik, Iqaluit, Rankin Inlet, Resolute and Yellowknife did not
observe DST in 1965, and did observe DST from 1972 through 1979.

Whitehorse moved from -09 to -08 on 1966-02-27, not 1967-05-28.

Colombia's 1993 fallback was 02-06 24:00, not 04-04 00:00. (Thanks to Alois
Treindl.)

Singapore's 1981-12-31 change was at 16:00 UTC (23:30 local time), not 24:00
local time. (Thanks to Geoff Clare via Robert Elz.)

2022.6: Release of upstream tzdata 2022f

Version 2022.6

Upstream version 2022f released 2022-10-29T01:04:57+00:00

Briefly:

Mexico will no longer observe DST except near the US border. Chihuahua moves to
year-round -06 on 2022-10-30. Fiji no longer observes DST. Move links to
'backward'. In vanguard form, GMT is now a Zone and Etc/GMT a link. zic now
supports links to links, and vanguard form uses this. Simplify four Ontario
zones. Fix a Y2438 bug when reading TZif data. Enable 64-bit time_t on 32-bit
glibc platforms. Omit large-file support when no longer needed. In C code, use
some C23 features if available. Remove no-longer-needed workaround for Qt bug
53071.

Changes to future timestamps.

Mexico will no longer observe DST after 2022, except for areas near the US
border that continue to observe US DST rules. On 2022-10-30 at 02:00 the Mexican
state of Chihuahua moves from -07 (-06 with DST) to year-round -06, thus not
changing its clocks that day. The new law states that Chihuahua near the US
border no longer observes US DST.

Fiji will not observe DST in 2022/3. (Thanks to Shalvin Narayan.) For now,
assume DST is suspended indefinitely.

Changes to data

Move links to 'backward' to ease and simplify link maintenance. This affects
generated data only if you use 'make BACKWARD='.

GMT is now a Zone and Etc/GMT a link instead of vice versa, as GMT is needed for
leap second support whereas Etc/GMT is not. However, this change exposes a bug
in TZUpdater 2.3.2 so it is present only in vanguard form for now.

Vanguard form now uses links to links, as zic now supports this.

Changes to past timestamps

Simplify four Ontario zones, as most of the post-1970 differences seem to have
been imaginary. (Problem reported by Chris Walton.) Move America/Nipigon,
America/Rainy_River, and America/Thunder_Bay to 'backzone'; backward-
compatibility links still work, albeit with some different timestamps before
November 2005.

2022.5: Release of upstream tzdata 2022e

Version 2022.5

Upstream version 2022e released 2022-10-11T18:13:02+00:00

Briefly:

Jordan and Syria switch from +02/+03 with DST to year-round +03.

Changes to future timestamps

Jordan and Syria are abandoning the DST regime and are changing to permanent
+03, so they will not fall back from +03 to +02 on 2022-10-28. (Thanks to
Steffen Thorsen and Issam Al-Zuwairi.)

Changes to past timestamps

On 1922-01-01 Tijuana adopted standard time at 00:00, not 01:00.

Changes to past time zone abbreviations and DST flags

The temporary advancement of clocks in central Mexico in summer 1931 is now
treated as daylight saving time, instead of as two changes to standard time.

2022.4: Release of upstream tzdata 2022d

Version 2022.4

Upstream version 2022d released 2022-09-23T19:02:57+00:00

Briefly:

Palestine transitions are now Saturdays at 02:00. Simplify three Ukraine zones
into one.

Changes to future timestamps

Palestine now springs forward and falls back at 02:00 on the first Saturday on
or after March 24 and October 24, respectively. This means 2022 falls back 10-29
at 02:00, not 10-28 at 01:00. (Thanks to Heba Hamad.)

Changes to past timestamps

Simplify three Ukraine zones to one, since the post-1970 differences seem to
have been imaginary. Move Europe/Uzhgorod and Europe/Zaporozhye to 'backzone';
backward-compatibility links still work, albeit with different timestamps before
October 1991.

2022.3: Release of upstream tzdata 2022c

Version 2022.3

Upstream version 2022c released 2022-08-16T00:47:18+00:00

Briefly:

Work around awk bug in FreeBSD, macOS, etc. Improve tzselect on intercontinental
Zones.

2022.2: Release of upstream tzdata 2022b

Version 2022.2

Upstream version 2022b released 2022-08-10T22:38:32+00:00

Briefly:

Chile's DST is delayed by a week in September 2022. Iran no longer observes DST
after 2022. Rename Europe/Kiev to Europe/Kyiv. New zic -R option Vanguard form
now uses %z. Finish moving duplicate-since-1970 zones to 'backzone'. New build
option PACKRATLIST New tailored_tarballs target, replacing rearguard_tarballs

Changes to future timestamps

Chile's 2022 DST start is delayed from September 4 to September 11. (Thanks to
Juan Correa.)

Iran plans to stop observing DST permanently, after it falls back on 2022-09-21.
(Thanks to Ali Mirjamali.)

Changes to past timestamps

Finish moving to 'backzone' the location-based zones whose timestamps since 1970
are duplicates; adjust links accordingly. This change ordinarily affects only
pre-1970 timestamps, and with the new PACKRATLIST option it does not affect any
timestamps. In this round the affected zones are Antarctica/Vostok, Asia/Brunei,
Asia/Kuala_Lumpur, Atlantic/Reykjavik, Europe/Amsterdam, Europe/Copenhagen,
Europe/Luxembourg, Europe/Monaco, Europe/Oslo, Europe/Stockholm,
Indian/Christmas, Indian/Cocos, Indian/Kerguelen, Indian/Mahe, Indian/Reunion,
Pacific/Chuuk, Pacific/Funafuti, Pacific/Majuro, Pacific/Pohnpei, Pacific/Wake
and Pacific/Wallis, and the affected links are Arctic/Longyearbyen,
Atlantic/Jan_Mayen, Iceland, Pacific/Ponape, Pacific/Truk, and Pacific/Yap.

From fall 1994 through fall 1995, Shanks wrote that Crimea's DST transitions
were at 02:00 standard time, not at 00:00. (Thanks to Michael Deckers.)

Iran adopted standard time in 1935, not 1946. In 1977 it observed DST from
03-21 23:00 to 10-20 24:00; its 1978 transitions were on 03-24 and 08-05, not
03-20 and 10-20; and its spring 1979 transition was on 05-27, not 03-21. (Thanks
to Roozbeh Pournader and Francis Santoni.)

Chile's observance of -04 from 1946-08-29 through 1947-03-31 was considered DST,
not standard time. Santiago and environs had moved their clocks back to rejoin
the rest of mainland Chile; put this change at the end of 1946-08-28. (Thanks
to Michael Deckers.)

Some old, small clock transitions have been removed, as people at the time did
not change their clocks. This affects Asia/Hong_Kong in 1904, Asia/Ho_Chi_Minh
in 1906, and Europe/Dublin in 1880.

Changes to zone name

Rename Europe/Kiev to Europe/Kyiv, as "Kyiv" is more common in English now.
Spelling of other names in Ukraine has not yet demonstrably changed in common
English practice so for now these names retain old spellings, as in other
countries (e.g., Europe/Prague not "Praha", and Europe/Sofia not "Sofiya").

2022.1: Release of upstream tzdata 2022a

Version 2022.1

Upstream version 2022a released 2022-03-16T06:02:01+00:00

Briefly:

Palestine will spring forward on 2022-03-27, not -03-26. zdump -v now outputs
better failure indications. Bug fixes for code that reads corrupted TZif data.

Changes to future timestamps

Palestine will spring forward on 2022-03-27, not 2022-03-26. (Thanks to Heba
Hamad.) Predict future transitions for first Sunday >= March 25. Additionally,
predict fallbacks to be the first Friday on or after October 23, not October's
last Friday, to be more consistent with recent practice. The first differing
fallback prediction is on 2025-10-24, not 2025-10-31.

Changes to past timestamps

From 1992 through spring 1996, Ukraine's DST transitions were at 02:00 standard
time, not at 01:00 UTC. (Thanks to Alois Treindl.)

Chile's Santiago Mean Time and its LMT precursor have been adjusted eastward by
1 second to align with past and present law.

Changes to commentary

Add several references for Chile's 1946/1947 transitions, some of which only
affected portions of the country.

2021.5: Release of upstream tzdata 2021e

Version 2021.5

Upstream version 2021e released 2021-10-22T01:41:00+00:00

Changes to future timestamps

Palestine will fall back 10-29 (not 10-30) at 01:00. (Thanks to P Chan and Heba Hemad.)

2021.4: Release of upstream tzdata 2021d

Version 2021.4

Upstream version 2021d released 2021-10-15T20:48:18+00:00

Briefly:

Fiji suspends DST for the 2021/2022 season. 'zic -r' marks unspecified
timestamps with "-00".

Changes to future timestamps

Fiji will suspend observance of DST for the 2021/2022 season. Assume for now
that it will return next year. (Thanks to Jashneel Kumar and P Chan.)