November 2025 - tz - lists.iana.org

backward file for zonenow.tab?
by kirill.gagarski＠gmail.com Nov. 17, 2025

Nov. 17, 2025

Hi. Our software tries to expose a list of supported timezones to an end user for setting up some periodic scheduled task in the UI. Till now we've tried to populate the list of Java supported timezones, filtering out aliases (from backward file). I noticed that zonedata now ships with zonenow.tab file which is exactly what we need for our UI and meets our needs more precisely. Unfortunately it seems quite impossible to migrate old data to this new notation automatically. For example, hte fact that 'Europe/Berlin' is covered by 'Europe/Paris' in zonenow.tab is not mentioned anywhere. Is there a way to determine this fact from tzdata without deep analysis of the rules done by myself? Other simple question: is there a way to know what is "now" in zonenow? Is it defined by the release date of a new version?

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Calendrical Issues Russia section
by Kirill Gagarski Nov. 14, 2025

Nov. 14, 2025

I fully understand that I am trying to engage into a 30 y.o discussion now, but the Russia section in calendars file repeats quite widespread myths about Eternal Calendar with 30th February. I used to believe in that myself, given quite a little information on the internet about the issue. Even Wikipedia spread this myth back in the day. Even the Russian version of Wikipedia spreaded the myth: https://ru.wikipedia.org/w/index.php?title=%D0%9D%D0%B5%D0%BF%D1%80%D0%B5%D… Nowadays, Wikipedia is more clean about the issue, providing some source links: https://ru.wikipedia.org/wiki/%D0%9D%D0%B5%D0%BF%D1%80%D0%B5%D1%80%D1%8B%D0… https://en.wikipedia.org/wiki/Soviet_calendar The truth is: - Gregorian calendar was continuously used during the mentioned time - 30th February in USSR is an absolute myth (to be more clear, this is a declined proposal of a new calendar) - Mentioned 5-day weeks and 6-day weeks were in fact an attempt to relabel weekdays (Monday-Sunday) - Relabeling was done in a way, not conflicting with traditional weekdays (they used words like "third day of six-week day" or colors). Traditional names were used in parallel I could not say, the calendar file does not say the truth (after all, it raises doubts in a second quoted message), and all this information is indeed very interesting from a historical point of view, but does not seem relevant to Calendrical Issues. In fact 100 years later no one (unless someone is specifically interested in these weird weekdays) cares if 12th of December of 1937 was "sixth day of six-day week", because it was Sunday at the same time. I'd suggest removing the whole Russia section from this file (you can keep the small note about switching from Julia to Gregorian calendar in 1918), since for the purpose of it it raises nothing but confusion.

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[PROPOSED] Fix unlikely backslash bug in scripts
by Paul Eggert Nov. 12, 2025

Nov. 12, 2025

* tzselect.ksh, workman.sh: Use printf, not echo, if the argument might in theory contain a backslash. --- tzselect.ksh | 9 +++++---- workman.sh | 2 +- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/tzselect.ksh b/tzselect.ksh index 7cd8679d..85a8c670 100644 --- a/tzselect.ksh +++ b/tzselect.ksh @@ -145,9 +145,11 @@ do t*) # Undocumented option, used for developer testing. zonetabtype=$OPTARG;; -help) - exec echo "$usage";; + say "$usage" + exit;; -version) - exec echo "tzselect $PKGVERSION$TZVERSION";; + say "tzselect $PKGVERSION$TZVERSION" + exit;; -*) say >&2 "$0: -$opt$OPTARG: unknown option; try '$0 --help'"; exit 1;; *) @@ -516,8 +518,7 @@ while ' ="$distance_table" ) echo >&2 'Please select one of the following timezones,' - echo >&2 'listed roughly in increasing order' \ - "of distance from $coord". + say >&2 "listed roughly in increasing order of distance from $coord." doselect $regions region=$select_result tz=$( diff --git a/workman.sh b/workman.sh index 91621b10..5da55654 100644 --- a/workman.sh +++ b/workman.sh @@ -51,6 +51,6 @@ elif (type nroff && type perl) >/dev/null 2>&1; then } ' else - echo >&2 "$0: please install groff, or mandoc and col" + printf >&2 '%s\n' "$0: please install groff, or mandoc and col" exit 1 fi -- 2.51.0

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Melbourne's Shrine of Remembrance
by Tim Parenti Nov. 11, 2025

Nov. 11, 2025

Earlier this year, Julian O'Shea released a short video detailing a peculiarity about the Shrine of Remembrance in Melbourne, "How Daylight Savings Broke this $24 Million Building": https://www.youtube.com/watch?v=mfzsBMUiGGQ The shrine, originally dedicated in 1934 to honor those who served in World War I, was designed with a small aperture in the roof. Each Remembrance Day (11 November) at 11:00am local time, the position of the sun would be perfectly aligned to shine through the aperture, allowing the light of its rays to fall upon an inscribed stone inside, thus commemorating the hour of the Armistice. The problem? Several decades later, in 1971, Victoria adopted DST, but of course the aperture had been tuned to the position of the sun at 11:00am AEST. So what do you do to preserve this meaningful element of an annual ceremony with important dignitaries, when it's effectively been moved an hour earlier to 11:00am AEDT instead? The answer involves a clever system of mirrors. (And the general public still gets to witness the light following its true path an hour later!) Since this is quite a grand physical representation of how we interact with our timekeeping, I've added this to tz-art.html, as well as a few fixups to unclosed HTML tags nearby. -- Tim Parenti

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Cape Town
by Justin Singh Nov. 10, 2025

Nov. 10, 2025

Hello The Timezone for Cape Town is UTC+01:00 The western Northern Cape and Western Cape differ, however. Everywhere on land west of 22°30′ E effectively experiences year-round daylight saving time because of its location in true UTC+01:00 but still being in South African Standard Time. Sunrise and sunset are thus relatively late in Cape Town, compared to the rest of the country.

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Nunavik to stop changing its clocks after March 2026?
by Paul Eggert Nov. 8, 2025

Nov. 8, 2025

Yesterday’s CBC News report “Nunavimmiut have wound back their clocks for the last time”[1] is so light on details that for now I am merely attaching a draft patch to this email for review, rather than installing the patch into the development repository. I found no announcement of the change at www.makivvik.ca. Although I asked for more details by using the form at <https://www.makivvik.ca/contact/>, these sorts of contact forms often do not work, so if anyone has access to more-authoritative info than the CBC report, please let us know. Among other things, details in the news report make me wonder how likely Makivvik would reconsider its decision before the change would take effect about a year from now. [1]: https://www.cbc.ca/news/canada/north/nunavik-daylight-savings-9.6969650

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Phoenix AZ timezone issue
by akbar＠marketing-qa.com Nov. 5, 2025

Nov. 5, 2025

🧭 Problem Summary Arizona remains one of the few U.S. states that does not observe Daylight Saving Time (DST) since 1968. However, it identifies its time zone as Mountain Standard Time (MST) — which does change to MDT when DST applies elsewhere. Because of this, every spring and fall, Arizona’s effective time alignment shifts: In summer, Arizona matches Pacific Daylight Time (PDT). In winter, it matches Mountain Standard Time (MST). This causes systemic issues in digital calendars, automated scheduling, flight bookings, and cross-state business coordination, requiring frequent manual adjustments. 💡 Recommended Solution Create and declare a dedicated time zone: “Phoenix Standard Time.” This would be a fixed, non-DST time zone officially recognized by IANA (the Internet Assigned Numbers Authority) and major platforms (Microsoft, Apple, Google). All digital devices could use it as a unique time zone identifier that never shifts with DST — eliminating confusion and rescheduling errors. It would function similarly to “UTC+7” year-round but would display as “Phoenix Standard Time (PST)” in software systems. Thank you Akbar Jaffer Akbar Jaffer Office: (415) 335-6950 Mobile: (650) 430-0232 Web: Marketing-QA.com <http://www.marketing-qa.com/> Meeting: Book time W/Akbar <https://calendly.com/ajaffer/> LinkedIn <https://www.linkedin.com/in/akbarjaffer/> | POI Blog <https://pointofintersection.org/>

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How to select zones for a TimeZone picker
by Guillermo Rodriguez Garcia Nov. 3, 2025

Nov. 3, 2025

Hi all, I'm building a TimeZone picker with the following constraints: 1. At least one distinct timezone per country (so that e.g. there is an entry for Atlantic/Reykjavik instead of mapping IS to Africa/Abidjan) 2. Within a country, do not show timezones that currently have identical rules to another timezone in the same country (i.e. historical differences don't matter). Because of (1) I started from zone.tab rather than zone1970.tab. However, I'm not sure how to handle (2). For example, Spain has three zones in zone.tab: Europe/Madrid, Africa/Ceuta, and Atlantic/Canary. But as far as most users are concerned, as of today there are only two timezones in Spain: Madrid and Canary Islands. Ceuta follows Madrid rules, so there should be no need to show this as an option to the user. Another example: the U.S. lists 29 zones, but only 8 are distinct today (ignoring historical changes). So, the question: Any suggestions on how to filter timezones within each country to drop those that as of today are not relevant except for historical differences? Thank you, Guillermo Rodriguez Garcia guille.rodriguez(a)gmail.com

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[PROPOSED] tzfree now preserves errno
by Paul Eggert Nov. 3, 2025

Nov. 3, 2025

* Makefile, NEWS, newtzset.3: Mention this. * localtime.c (FREE_PRESERVES_ERRNO): Default to 1 if 'free' is known to preserve errno, 0 otherwise. (tzfree): Preserve errno if 'free' does not. --- Makefile | 2 ++ NEWS | 2 ++ localtime.c | 15 +++++++++++++++ newtzset.3 | 4 ++++ 4 files changed, 23 insertions(+) diff --git a/Makefile b/Makefile index 0fe8a9f8..0d33fa17 100644 --- a/Makefile +++ b/Makefile @@ -239,6 +239,8 @@ LDLIBS= # -DEPOCH_OFFSET=N if the 'time' function returns a value N greater # than what POSIX specifies, assuming local time is UT. # For example, N is 252460800 on AmigaOS. +# -DFREE_PRESERVES_ERRNO=[01] if the 'free' function munges or preserves errno +# (default is guessed) # -DHAVE_DECL_ASCTIME_R=0 if <time.h> does not declare asctime_r # on POSIX platforms predating POSIX.1-2024 # -DHAVE_DECL_ENVIRON if <unistd.h> declares 'environ' diff --git a/NEWS b/NEWS index 1ed9b2eb..a9b2d321 100644 --- a/NEWS +++ b/NEWS @@ -93,6 +93,8 @@ Unreleased, experimental changes option is incompatible with POSIX.1-2024 and earlier. It also costs CPU time and memory. + tzfree now preserves errno, consistently with POSIX.1-2024 'free'. + tzcode now uses mempcpy if available, guessing its availability. Compile with -DHAVE_MEMPCPY=1 or 0 to override the guess. diff --git a/localtime.c b/localtime.c index b85941f2..46acf3bd 100644 --- a/localtime.c +++ b/localtime.c @@ -2061,10 +2061,25 @@ tzalloc(char const *name) return sp; } +#ifndef FREE_PRESERVES_ERRNO +# if ((defined _POSIX_VERSION && 202405 <= _POSIX_VERSION) \ + || (defined __GLIBC__ && 2 < __GLIBC__ + (33 <= __GLIBC_MINOR__)) \ + || defined __OpenBSD__ || defined __sun) +# define FREE_PRESERVES_ERRNO 1 +# else +# define FREE_PRESERVES_ERRNO 0 +# endif +#endif + void tzfree(timezone_t sp) { + int err; + if (!FREE_PRESERVES_ERRNO) + err = errno; free(sp); + if (!FREE_PRESERVES_ERRNO) + errno = err; } /* diff --git a/newtzset.3 b/newtzset.3 index 3801ab1b..028cfd25 100644 --- a/newtzset.3 +++ b/newtzset.3 @@ -379,6 +379,10 @@ If successful, the function returns a nonnull pointer to the newly allocated object. Otherwise, it returns a null pointer and sets .IR errno . +The +.B tzfree +function does not modify +.IR errno . .SH ERRORS .TP .B EOVERFLOW -- 2.51.0

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