tzdb 2023d: 4 time zone changes

Published: December 21, 2023 · Automatically generated from source data.

Published on Time Dozen: October 7, 2026

Briefly

Ittoqqortoormiit, Greenland (America/Scoresbysund) joins most of the rest of Greenland's timekeeping practice on 2024-03-31, by changing its time zone from -01/+00 to -02/-01 at the same moment as the spring-forward transition. Its clocks will therefore not spring forward as previously scheduled. The time zone change reverts to its common practice before 1981. (Thanks to Jule Dabars.)
Fix predictions for DST transitions in Palestine in 2072-2075, correcting a typo introduced in 2023a. (Thanks to Jule Dabars.)

Vostok, Antarctica changed to +05 on 2023-12-18. It had been at +07 (not +06) for years. (Thanks to Zakhary V. Akulov.)
Change data for Casey, Antarctica to agree with timeanddate.com, by adding five time zone changes since 2020. Casey is now at +08 instead of +11.

Other notes in this release (code, build procedure, documentation)

Much of Greenland, represented by America/Nuuk, changed its standard time from -03 to -02 on 2023-03-25, not on 2023-10-28. This does not affect UTC offsets, only the tm_isdst flag. (Thanks to Thomas M. Steenholdt.)
New data file
A new data file zonenow.tab helps configure applications that use timestamps dated from now on. This simplifies configuration, since users choose from a smaller Zone set. The file's format is experimental and subject to change.

localtime.c no longer mishandles TZif files that contain a single transition into a DST regime. Previously, it incorrectly assumed DST was in effect before the transition too. (Thanks to Alois Treindl for debugging help.)
localtime.c's timeoff no longer collides with OpenBSD 7.4.
The C code now uses _Generic only if __STDC_VERSION__ says the compiler is C11 or later.
tzselect now optionally reads zonenow.tab, to simplify when configuring only for timestamps dated from now on.
tzselect no longer creates temporary files.
tzselect no longer mishandles the following: Spaces and most other special characters in BUGEMAIL, PACKAGE, TZDIR, and VERSION. TZ strings when using mawk 1.4.3, which mishandles regular expressions of the form /X{2,}/. ISO 6709 coordinates when using an awk that lacks the GNU extension of newlines in -v option-arguments. Non UTF-8 locales when using an iconv command that lacks the GNU //TRANSLIT extension.
zic no longer mishandles data for Palestine after the year 2075. Previously, it incorrectly omitted post-2075 transitions that are predicted for just before and just after Ramadan. (Thanks to Ken Murchison for debugging help.)
zic now works again on Linux 2.6.16 and 2.6.17 (2006). (Problem reported by Rune Torgersen.)

The Makefile is now more compatible with POSIX:
It no longer defines AR, CC, CFLAGS, LDFLAGS, and SHELL.
It no longer uses its own 'cc' in place of CC.
It now uses ARFLAGS, with default specified by POSIX.
It does not use LFLAGS incompatibly with POSIX.
It uses the special .POSIX target.
It quotes special characters more carefully.
It no longer mishandles builds in an ISO 8859 locale. Due to the CC changes, TZDIR is now #defined in a file tzdir.h built by 'make', not in a $(CC) -D option. Also, TZDEFAULT is now treated like TZDIR as they have similar roles.

Limitations and hazards of the optional support for obsolescent C89 platforms are documented better, along with a tentative schedule for removing this support.