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KDS Calendar and projection-based time systems — question for TZ coordinators
by Dragan Škondrić May 27, 2026

May 27, 2026

Dear TZ Coordinators and list members, My name is Dragan Škondrić. I am an independent researcher and the author of *KDS Calendar Version 3.0*, a canon-first calendar-time specification. I am writing with a conceptual and architectural question, not with a request to change the IANA Time Zone Database. The core idea of KDS is that existing civil, legal, metrological, and software time systems — including UTC, Gregorian dates, local time zones, DST rules, ISO 8601 renderings, and TZDB-based local-time projections — may remain as projection-facing systems, while a separate canonical layer preserves invariant event identity. In short: *KDS proposes a canonical event-identity layer above projection-based time systems.* Under this framing, time zones and civil-time rules are not treated as errors or obsolete mechanisms. They remain essential projection systems for human, legal, and operational use. However, they are not treated as the primary identity of a preserved event. The event would instead carry a canonical identity, edition information, annual phase, canonical coordinates, source metadata, and projection profile information, so that different projections can be generated without collapsing the event identity into any one local-time rendering. I am aware that TZDB already solves a very different and highly practical problem: maintaining historical and current civil-time rule data for real-world locations. KDS is not proposed as a replacement for that work. My question is narrower: Does the distinction between *canonical event identity* and *civil/time-zone projection* seem technically meaningful from the perspective of people who maintain or use TZDB? A related question is whether there are existing terms, prior discussions, or known models in the time-zone / civil-time community that already address this separation between: 1. the identity of an event, 2. the instant or time scale used for ordering, 3. the local civil-time rendering, 4. and the future replay of that event under changing time-zone or calendar rules. The specification is archived on Zenodo: *KDS Calendar - Version 3.0* DOI: *10.5281/zenodo.20067725* At this stage I am not asking for endorsement, adoption, or any change to TZDB. I would simply appreciate any technical comments on whether this framing is meaningful, already covered by existing practice, or conceptually misplaced from the viewpoint of the TZDB community. Kind regards, *Dragan Škondrić*

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Missing record Madeira Island DST
by Stefanie Schlosser May 26, 2026

May 26, 2026

Dear IANA team, For personal reasons, I've been trying to find out about DST on Madeira Island, Portugal during the past century. Long story short. I've researched a lot and along the way I've been told that even IANA is actually missing some records for when Madeira Island was congruent in its time changes with mainland Portugal (Lisbon) and when it did its own thing. I've eventually found the original law text for Madeira Island from 1982 and am hereby submitting it to you. You don't have any mistake in your tzdb, but seemingly part of it is based on the assumption that Madeira did not apply DST under certain years, and you didn't have prove of it. Here comes the prove. :) With best regards, Stefanie Schlosser

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US permanent DST to make its way into transportation funding bill
by Tim Parenti May 22, 2026

May 22, 2026

Many on this list will remember the *Sunshine Protection Act of 2021* passing the US Senate in March 2022 by unanimous consent in uncharacteristically swift fashion: https://lists.iana.org/hyperkitty/list/tz@iana.org/thread/GRBDSXXXWM4XXNERF… Following near-immediate blowback from a few senators — including Senator Tom Cotton of Arkansas, who says his staff had not properly flagged it for his opposition — the effort ultimately stalled in the House. When sponsors of functionally identical legislation in the current Congress similarly attempted to fast-track it in October 2025, Cotton blocked the effort. https://thehill.com/homenews/nexstar_media_wire/5581335-effort-to-fast-trac… *The Hill* now reports this week that the legislation is receiving a full markup by the House Energy and Commerce Committee, and will be rolled into the *Motor Vehicle Modernization Act*, a larger transportation funding package. https://thehill.com/homenews/house/5886117-daylight-saving-time-house-repub… https://thehill.com/policy/5889199-permanent-daylight-saving-time-legislati… https://thehill.com/homenews/administration/5890568-trump-praises-daylight-… President Donald Trump, who last year admitted to press that DST reform is a "50/50 issue" which "it's hard to get excited about", praised the committee's vote on Thursday, calling it "a very nice win for the Republican Party" and saying he is "going to work very hard" to see the act signed into law. https://truthsocial.com/@realDonaldTrump/posts/116615022975327653 If adopted as-is, states that do not join Arizona and Hawaii in opting for the existing "standard time" exemption prior to the new law taking effect would automatically be placed into "permanent daylight time". The text does not currently carry any delay provision, nor does it allow for states to opt in or out of DST after it is adopted. https://www.congress.gov/bill/119th-congress/house-bill/139/text https://www.congress.gov/bill/119th-congress/house-bill/7389/text -- Tim Parenti

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Manitoba DST survey underway
by Tim Parenti May 22, 2026

May 22, 2026

Following on from Manitoba Premier Wab Kinew's recent statements to press that "the days of Manitoba switching the clocks twice a year are pretty much at the end"… https://lists.iana.org/hyperkitty/list/tz@iana.org/thread/MLTAPD5WO23WH5MFB… CBC and Global report on social media posts from the premier's office this week, encouraging Manitobans to take a survey on the future of semi-annual time changes: https://www.cbc.ca/news/canada/manitoba/time-change-survey-9.7205662 https://globalnews.ca/news/11856999/manitoba-survey-daylight-savings/ "[The survey] asks specifically which option residents would like to see. Choices include permanent daylight time, permanent standard time, sticking to the status quo and keeping time changes and a final option for no preference." A government spokesperson has said the survey will run through 31 August 2026, so we will probably not see legislative action until the Assembly's fall sitting which is scheduled from 29 September to 3 December 2026. It seems, then, that clocks in Manitoba will likely fall back to UTC−6 on 1 November 2026 as scheduled and either (a) stay there, adopting a "permanent standard time"/"Prairie time zone", (b) spring forward a final time to UTC−5 on 14 March 2027, or (c) maintain the *status quo*. Whichever the outcome, scheduled offsets are not likely to be affected until sometime in 2027. The survey is available in both English and French here: https://engagemb.ca/time-change https://participationmb.ca/changement-d-heure -- Tim Parenti

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[PATCH] Let build environment override _, N_
by Paul Eggert May 19, 2026

May 19, 2026

This is helpful when building this code inside glibc. Problem reported by Adhemerval Zanella Netto in: https://sourceware.org/pipermail/libc-alpha/2026-May/177497.html * private.h (_, N_): Don’t define if already defined. --- private.h | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/private.h b/private.h index ee191b4e..1e6db08c 100644 --- a/private.h +++ b/private.h @@ -1071,12 +1071,16 @@ time_t timeoff(struct tm *, long); ** The default is to use gettext if available, and use MSGID otherwise. */ -#if HAVE_GETTEXT -# define _(msgid) gettext(msgid) -#else /* !HAVE_GETTEXT */ -# define _(msgid) (msgid) -#endif /* !HAVE_GETTEXT */ -#define N_(msgid) (msgid) +#ifndef _ +# if HAVE_GETTEXT +# define _(msgid) gettext(msgid) +# else +# define _(msgid) (msgid) +# endif +#endif +#ifndef N_ +# define N_(msgid) (msgid) +#endif #if !defined TZ_DOMAIN && defined HAVE_GETTEXT # define TZ_DOMAIN "tz" -- 2.53.0

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Alberta to follow British Columbia?
by Roozbeh Pournader May 15, 2026

May 15, 2026

I just ran into this: https://calgaryherald.com/opinion/columnists/bell-alberta-daylight-time-yea…

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BC considering “PacT” to abbreviate Pacific Time
by Paul Eggert May 14, 2026

May 14, 2026

The BC government is considering recommending the abbreviation “PacT” for Pacific Time as observed in British Columbia since 2026-03-09. Two draft TZDB patches are attached that would implement this. The first simply changes “MST” to “PacT” for timestamps starting 2026-11-01, in line with 2026b’s temporary hack to delay this transition because the downstream user CLDR v48.2 (2026-03-17) cannot support BC’s current timekeeping. The second patch removes the temporary hack, adjusting TZDB to better reflect BC’s timekeeping, in the hope that the temporary hack is no longer needed once the abbreviation changes from “MST” to “PacT”. I have not installed these patches into the TZDB development repository, as “PacT” is still under consideration. Comments are welcome as usual.

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Re: research on TZ list
by Michelle Bastian May 13, 2026

May 13, 2026

Dear all, I'm following up from a 2021 post where I let the list know about an academic research project I was planning which involved an analysis of the list discussion. I have now had a chance to finally start on this. I said at the time that I would get back in touch to ask permissions from anyone I would like to quote directly in my write up. Since the tz discussion list is searchable, this would mean that I could not fully anonymise those I quote as is the usual default practice in my field. This email to the full list is just to update everyone on the project, and let people know that I will contact some posters individually through the email they shared with this list. There is no pressure at all to agree, in fact you can ask me to remove any of your comments entirely. If I don't hear back after my first email I will send one follow up, but after that I will assume that you would rather not be involved. If you are happy to be included, I will share an information sheet that explains in detail what I'm asking for, and what to consider when making a decision, as well as consent form. Thanks all! Earlier post: https://lists.iana.org/hyperkitty/list/tz@iana.org/message/OTOYYCADZ7P5BUQX… With best wishes, Michelle. --- Dr Michelle Bastian Senior Lecturer in Environmental Humanities ESALA, Edinburgh College of Art, University of Edinburgh Level 1, Room 303B, The Maltings | Minto House, 20-22 Chambers Street, Edinburgh, EH1 1JZ | 0131 651 5779 https://www.eca.ed.ac.uk/profile/dr-michelle-bastian The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. Is e buidheann carthannais a th' ann an Oilthigh Dh?n ?ideann, cl?raichte an Alba, ?ireamh cl?raidh SC005336.

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[PROPOSED] Adjust to GCC 16’s warnings
by Paul Eggert May 9, 2026

May 9, 2026

* Makefile (GCC_DEBUG_FLAGS): Add -Wfree-labels, -Wkeyword-macro. --- Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index c0dde5be..3428e8fd 100644 --- a/Makefile +++ b/Makefile @@ -377,7 +377,8 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 \ -Wdeclaration-after-statement -Wdouble-promotion \ -Wduplicated-branches -Wduplicated-cond -Wflex-array-member-not-at-end \ -Wformat=2 -Wformat-overflow=2 -Wformat-signedness -Wformat-truncation \ - -Wimplicit-fallthrough=5 -Winit-self -Wlogical-op \ + -Wfree-labels -Wimplicit-fallthrough=5 -Winit-self \ + -Wkeyword-macro -Wlogical-op \ -Wmissing-declarations -Wmissing-prototypes \ -Wmissing-variable-declarations -Wnested-externs \ -Wnull-dereference \ -- 2.54.0

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[PROPOSED] Update commentary for Winnipeg in 1916 and 1960s
by Paul Eggert May 8, 2026

May 8, 2026

* northamerica: Update commentary in the light of Christian Cassidy’s article published two days ago. Although it seems that our data for America/Winnipeg in the 1960s are incorrect, as yet we have no better sources than Shanks & Pottenger. --- northamerica | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/northamerica b/northamerica index 3e8641e1..6198e72e 100644 --- a/northamerica +++ b/northamerica @@ -1742,6 +1742,22 @@ Zone America/Toronto -5:17:32 - LMT 1895 # Manitoba +# From Paul Eggert (2026-05-08): +# For 1916 timestamps America/Winnipeg covers only a small region. See: +# Cassidy C. Winnipeg's 100-year history with daylight time. +# Winnipeg Free Press. 2026-05-06. +# https://www.winnipegfreepress.com/our-communities/correspondents/2026/05/06… +# Of the 1916 experiment, Cassidy writes: "As rural areas and nearby +# urban centres such as Selkirk and Brandon did not adopt DST, the +# City of Winnipeg essentially had its own time zone." Cassidy also +# writes that province-wide DST came into effect on 1963-05-12. +# +# Shanks & Pottenger write that Winnipeg did not observe DST in 1964 and 1965. +# Although dubious in the light of Cassidy's article, we lack a better source. +# Perhaps S&P's data are for the train stations, not for the city? +# Also, S&P say Manitoba switched at 02:00 (not 02:00s) starting in 1966. +# Since 02:00s is clearly correct for 1967 on, assume 02:00s in 1966 too. + # From Rob Douglas (2006-04-06): # the old Manitoba Time Act - as amended by Bill 2, assented to # March 27, 1987 ... said ... @@ -1756,11 +1772,6 @@ Zone America/Toronto -5:17:32 - LMT 1895 # the 1987 version would apply - the changeover was at 2:00 Central # Standard Time (i.e. not until 3:00 Central Daylight Time). -# From Paul Eggert (2006-04-10): -# Shanks & Pottenger say Manitoba switched at 02:00 (not 02:00s) -# starting 1966. Since 02:00s is clearly correct for 1967 on, assume -# it was also 02:00s in 1966. - # Rule NAME FROM TO - IN ON AT SAVE LETTER/S Rule Winn 1916 only - Apr 23 0:00 1:00 D Rule Winn 1916 only - Sep 17 0:00 0 S -- 2.51.0

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