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    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 code

    You can now tell tzselect local time, to simplify later choices.
    Select the 'time' option in its first prompt.

    You can now compile with -DTZNAME_MAXIMUM=N to limit time zone
    abbreviations to N bytes (default 255).  The reference runtime
    library now rejects POSIX-style TZ strings that contain longer
    abbreviations, treating them as UTC.  Previously the limit was
    platform dependent and abbreviations were silently truncated to
    16 bytes even when the limit was greater than 16.

    The code by default is now designed for C99 or later.  To build on
    a mostly-C89 platform, compile with -DPORT_TO_C89; this should
    work on C89 platforms that also support C99 'long long' and
    perhaps a few other extensions to C89.  To support C89 callers of
    tzcode's library, compile with -DSUPPORT_C89; however, this could
    trigger latent bugs in C99-or-later callers.  The two new macros
    are transitional aids planned to be removed in a future version
    (say, in 2029), when C99 or later will be required.

    The code now builds again on pre-C99 platforms, if you compile
    with -DPORT_TO_C89.  This fixes a bug introduced in 2022f.

    On C23-compatible platforms tzcode no longer uses syntax like
    'static [[noreturn]] void usage(void);'.  Instead, it uses
    '[[noreturn]] static void usage(void);' as strict C23 requires.
    (Problem reported by Houge Langley.)

    The code's functions now constrain their arguments with the C
    'restrict' keyword consistently with their documentation.
    This may allow future optimizations.

    zdump again builds standalone with ckdadd and without setenv,
    fixing a bug introduced in 2022g.  (Problem reported by panic.)

    leapseconds.awk can now process a leap seconds file that never
    expires; this might be useful if leap seconds are discontinued.

  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 there are plans to discontinue leap seconds by 2035.


Release 2022g - 2022-11-29 08:58:31 -0800

  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.)