- tz - lists.iana.org

manual pages in tzdb
by Alejandro Colomar May 12, 2024

May 12, 2024

Hi Paul, I had in mind something: I would like to cherry-pick all tzdb's commits that affect manual pages into the Linux man-pages git repository, instead of just pasting here snapshots of your manual pages. For that to work, we'd need to agree on a path inside the repository (or I could manually --or with a script-- edit each commit, which would be combersome, and I'd rather avoid). What do you think of moving the pages in the tzdb repository into man/man*/ directories? I see your repository is perfectly flat, so I don't know if there are strong reasons for that, or if it's just innertia. To be explicit, this is what I'd do in tzdb.git: diff --git a/date.1 b/man/man1/date.1 similarity index 100% rename from date.1 rename to man/man1/date.1 diff --git a/newctime.3 b/man/man3/newctime.3 similarity index 100% rename from newctime.3 rename to man/man3/newctime.3 diff --git a/newstrftime.3 b/man/man3/newstrftime.3 similarity index 100% rename from newstrftime.3 rename to man/man3/newstrftime.3 diff --git a/newtzset.3 b/man/man3/newtzset.3 similarity index 100% rename from newtzset.3 rename to man/man3/newtzset.3 diff --git a/time2posix.3 b/man/man3/time2posix.3 similarity index 100% rename from time2posix.3 rename to man/man3/time2posix.3 diff --git a/tzfile.5 b/man/man5/tzfile.5 similarity index 100% rename from tzfile.5 rename to man/man5/tzfile.5 diff --git a/tzselect.8 b/man/man8/tzselect.8 similarity index 100% rename from tzselect.8 rename to man/man8/tzselect.8 diff --git a/zdump.8 b/man/man8/zdump.8 similarity index 100% rename from zdump.8 rename to man/man8/zdump.8 diff --git a/zic.8 b/man/man8/zic.8 similarity index 100% rename from zic.8 rename to man/man8/zic.8 If we do that, then my idea would be to do $ git remote add tzdb git@github.com:eggert/tz.git in my Linux man-pages local repo, and cherry-pick commits '-- man/' from time to time. Does that sound good to you? Have a lovely day! Alex -- <https://www.alejandro-colomar.es/> A client is hiring kernel driver, mm, and/or crypto developers; contact me if interested.

9 20

[PROPOSED] Update some URLs
by Paul Eggert May 8, 2024

May 8, 2024

--- theory.html | 2 +- tz-link.html | 40 +++++++++++++++++++--------------------- 2 files changed, 20 insertions(+), 22 deletions(-) diff --git a/theory.html b/theory.html index 5cb80d99..50e9ee4d 100644 --- a/theory.html +++ b/theory.html @@ -1088,7 +1088,7 @@ an older <code>zic</code>. and <code>localtime_rz</code> and <code>mktime_z</code> are like <code>localtime_r</code> and <code>mktime</code> with an extra <code>timezone_t</code> argument. - The functions were inspired by <a href="https://netbsd.org/">NetBSD</a>. + The functions were inspired by <a href="https://netbsd.org">NetBSD</a>. </li> <li> Negative <code>time_t</code> values are supported, on systems diff --git a/tz-link.html b/tz-link.html index 162d63ce..c6d96101 100644 --- a/tz-link.html +++ b/tz-link.html @@ -81,7 +81,7 @@ C Library</a> (used in title="Berkeley Software Distribution">BSD</abbr></a>, <a href="https://netbsd.org">Net<abbr>BSD</abbr></a>, <a href="https://www.openbsd.org">Open<abbr>BSD</abbr></a>, -<a href="https://www.chromium.org/chromium-os/">Chromium OS</a>, +<a href="https://www.chromium.org/chromium-os/">ChromiumOS</a>, <a href="https://cygwin.com">Cygwin</a>, <a href="https://mariadb.org">MariaDB</a>, <a href="https://en.wikipedia.org/wiki/MINIX">MINIX</a>, @@ -211,7 +211,7 @@ href="https://mm.icann.org/mailman/listinfo/tz">subscribe</a> to it and browse the <a href="https://mm.icann.org/pipermail/tz/">archive of old messages</a>. -<a href="https://tzdata-meta.timtimeonline.com/">Metadata for mailing list +<a href="https://tzdata-meta.timtimeonline.com">Metadata for mailing list discussions</a> and corresponding data changes can be generated <a href="https://github.com/timparenti/tzdata-meta">automatically</a>. </p> @@ -226,7 +226,7 @@ the process by tailoring the generic instructions in the <code><abbr>tz</abbr> README</code> file and installing the latest data yourself. System-specific instructions for installing the latest <code><abbr>tz</abbr></code> data have also been published -for <a href="https://developer.ibm.com/articles/au-aix-olson-time-zone/"><abbr>AIX</abbr></a>, +for <a href="https://www.ibm.com/support/pages/aix-time-zone-olson-tzdata-updates"><abbr>AIX</abbr></a>, <a href="https://source.android.com/devices/tech/config/timezone-rules">Android</a>, <a @@ -248,7 +248,7 @@ with lines terminated by <a href="https://en.wikipedia.org/wiki/Newline"><abbr title="linefeed">LF</abbr></a>, which can be modified by common text editors such as <a href="https://www.gnu.org/software/emacs/">GNU Emacs</a>, -<a href="https://wiki.gnome.org/Apps/Gedit">gedit</a>, and +<a href="https://gedit-technology.github.io/apps/gedit/">gedit</a>, and <a href="https://www.vim.org">vim</a>. Specialized source-file editing can be done via the <a href="https://packagecontrol.io/packages/zoneinfo">Sublime @@ -400,7 +400,7 @@ variant <a href="https://datatracker.ietf.org/doc/html/rfc6321">xCal</a> title="Extensible Markup Language">XML</abbr></a> format, and a variant <a href="https://datatracker.ietf.org/doc/html/rfc7265">jCal</a> (Internet <abbr>RFC</abbr> 7265) -uses <a href="https://www.json.org"><abbr +uses <a href="https://www.json.org/json-en.html"><abbr title="JavaScript Object Notation">JSON</abbr></a> format.</li> </ul> </section> @@ -440,11 +440,9 @@ transition in the <code><abbr>tz</abbr></code> database.</li> <li>The <a href="https://howardhinnant.github.io/date/tz.html">Time Zone Database Parser</a> is a <a href="https://en.wikipedia.org/wiki/C++">C++</a> parser and -runtime library with <a -href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0355r7.html">API</a> -adopted by -<a href="https://en.wikipedia.org/wiki/C++20">C++20</a>, -the current iteration of the C++ standard. +runtime library with a <a +href="https://en.cppreference.com/w/cpp/chrono"><code>std::chrono</code> API</a> +that is a standard part of C++. It is freely available under the <abbr title="Massachusetts Institute of Technology">MIT</abbr> license.</li> <li><a id="ICU" href="https://icu.unicode.org">International Components for @@ -467,8 +465,8 @@ freely available under the <abbr>MIT</abbr> license.</li> <li>The <a href="https://www.oracle.com/java/technologies/javase/tzupdater-readme.html">TZUpdater tool</a> compiles <code><abbr>tz</abbr></code> source into the format used by -<a href="https://openjdk.java.net/">OpenJDK</a> and -<a href="https://jdk.java.net/">Oracle JDK</a>. +<a href="https://openjdk.org">OpenJDK</a> and +<a href="https://jdk.java.net">Oracle JDK</a>. Although its source code is proprietary, its executable is available under the <a href="https://www.oracle.com/a/tech/docs/tzupdater-lic.html">Java SE Timezone Updater License Agreement</a>.</li> @@ -490,7 +488,7 @@ are alternatives to TZUpdater. IANA Updater's license is unclear; ZIUpdater is licensed under the <abbr>GPL</abbr>.</li> <li><a href="https://github.com/MenoData/Time4A">Time4A: Advanced date and time library for Android</a> and -<a href="https://github.com/MenoData/Time4J/">Time4J: Advanced date, +<a href="https://github.com/MenoData/Time4J">Time4J: Advanced date, time and interval library for Java</a> compile <code><abbr>tz</abbr></code> source into a binary format. Time4A is available under the Apache License and Time4J is @@ -516,7 +514,7 @@ many of which also support runtimes lacking the <code>timeZone</code> option. href="https://github.com/formatjs/date-time-format-timezone"><code>Intl.DateTimeFormat</code> timezone polyfill</a> is freely available under a <abbr>BSD</abbr>-style license.</li> -<li>The <a href="https://date-fns.org/">date-fns</a> +<li>The <a href="https://date-fns.org">date-fns</a> library manipulates timezone-aware timestamps in browsers and in <a href="https://nodejs.org/en/">Node.js</a>. It is freely available under the <abbr>MIT</abbr> license.</li> @@ -552,9 +550,9 @@ objects</a> let programs access an abstract view of <code><abbr>tzdb</abbr></code> data, and are designed to replace <a href="https://codeofmatt.com/javascript-date-type-is-horribly-broken/">JavaScript's problematic <code>Date</code> objects</a> when working with dates and times. -<li><a href="https://github.com/JuliaTime/">JuliaTime</a> contains a +<li><a href="https://github.com/JuliaTime">JuliaTime</a> contains a compiler from <code><abbr>tz</abbr></code> source into -<a href="https://julialang.org/">Julia</a>. It is freely available +<a href="https://julialang.org">Julia</a>. It is freely available under the <abbr>MIT</abbr> license.</li> <li><a href="https://github.com/pavkam/tzdb"><abbr>TZDB</abbr> – <abbr>IANA</abbr> Time Zone Database for Delphi/<abbr @@ -565,7 +563,7 @@ as compiled by <a href="https://en.wikipedia.org/wiki/Delphi_(IDE)">Delphi</a> and <a href="https://en.wikipedia.org/wiki/Free_Pascal"><abbr>FPC</abbr></a>. It is freely available under a <abbr>BSD</abbr>-style license.</li> -<li><a href="http://pytz.sourceforge.net">pytz – World Timezone +<li><a href="https://pythonhosted.org/pytz/">pytz – World Timezone Definitions for Python</a> compiles <code><abbr>tz</abbr></code> source into <a href="https://www.python.org">Python</a>. It is freely available under a <abbr>BSD</abbr>-style license. @@ -649,7 +647,7 @@ that represent <code><abbr>tzdb</abbr></code> timezones. Python is freely available under the <a href="https://docs.python.org/3/license.html">Python Software Foundation License</a>. -A companion <a id="pypi-tzdata" href="https://pypi.org/">PyPI</a> module +A companion <a id="pypi-tzdata" href="https://pypi.org">PyPI</a> module <a href="https://pypi.org/project/tzdata/"><code>tzdata</code></a> supplies TZif data if the underlying system data cannot be found; it is freely available under the Apache License.</li> @@ -898,7 +896,7 @@ href="https://www.ptb.de/cms/en/fachabteilungen/abt4/fb-44/ag-441/realisation-of of Legal Time in Germany</a>.</dd> <dt>Israel</dt> <dd><a -href="https://tz.cs.huji.ac.il/">Israel Timezone Files</a> +href="https://tz.cs.huji.ac.il">Israel Timezone Files</a> lists official time-change announcements and laws since 1940, almost all in Hebrew.</dd> <dt>Malaysia</dt> @@ -1087,9 +1085,9 @@ is well-defined for sufficiently old timestamps.</li> <code>leap-seconds.list</code>, which lists the currently known leap seconds. The <abbr>IERS</abbr> maintains this file, and a copy is distributed by <code><abbr>tzdb</abbr></code> for use by <abbr>NTP</abbr> implementations like -<a href="https://www.ntp.org/">classic +<a href="https://www.ntp.org">classic <code><abbr title="Network Time Protocol Daemon">ntpd</abbr></code></a> -and <a href="https://ntpsec.org/">NTPsec</a>. +and <a href="https://ntpsec.org">NTPsec</a>. The <code><abbr>tz</abbr></code> database also distributes leap second information in a differently-formatted <code>leapseconds</code> text file, as well as in the "<code>right</code>" configuration in binary form; for -- 2.40.1

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Why is "AEST" the abbreviation for Australia/Sydney in 1900?
by Jonathan Wakely May 8, 2024

May 8, 2024

Given this snippet from tzdata.zi: Z Australia/Sydney 10:4:52 - LMT 1895 F 10 AU AE%sT 1971 R AU 1917 o - Ja 1 2s 1 D R AU 1917 o - Mar lastSu 2s 0 S R AU 1942 o - Ja 1 2s 1 D R AU 1942 o - Mar lastSu 2s 0 S R AU 1942 o - S 27 2s 1 D R AU 1943 1944 - Mar lastSu 2s 0 S R AU 1943 o - O 3 2s 1 D What should the abbreviation be for the zone in, say, 1900? Using glibc I get AEST: TZ=Australia/Sydney date --date="1900-01-01" Mon 1 Jan 00:00:00 AEST 1900 But I don't see any way to get "AEST" from the tzdata and the spec in the zic(8) man page. Prior to 1895 it is "LMT", and then from 1917-01-01 it's "AEDT", and from 1917-03-25 it's "AEST", but none of the Rule lines apply to dates before 1917, so what value of LETTER/S should be used for the AE%sT format in 1900? Glibc solves this by iterating through all the transitions for the AU rule until it finds a valid name for a transition to DST and a valid name for a transition out of DST, and then remembers those two names, which in this case gives AEDT (from 1917-01-01 to 1917-03-25) and AEST (from 1917-03-25 to 1942-01-01). Then when it finds the info for a date in 1900 it looks at the isdst field of struct tm for that date, and picks one of the two remembered names, which gives us "AEST". That seems like the correct result, but nothing in the zic man page (or any other docs I can find) says that is what's supposed to happen. My code for GCC's C++ library is an independent implementation based on the spec, and it has no way to produce "AEST" for 1900. It seems to me that either the spec should to do ... something ... so that a LETTER/S field for the Rule can be found, or there should be a Zone continuation line in the tzdata that explicitly says that Australia/Sydney is always on standard time for the period 1895-02-01 to 1917-01-01 and that the abbreviation is AEST (without any %s that needs to be expanded). So add the second line here: Z Australia/Sydney 10:4:52 - LMT 1895 F 10 - AEST 1917 10 AU AE%sT 1971 R AU 1917 o - Ja 1 2s 1 D R AU 1917 o - Mar lastSu 2s 0 S R AU 1942 o - Ja 1 2s 1 D R AU 1942 o - Mar lastSu 2s 0 S R AU 1942 o - S 27 2s 1 D R AU 1943 1944 - Mar lastSu 2s 0 S R AU 1943 o - O 3 2s 1 D I'm sure this question could also be asked of many other zones, Australia/Sydney just happens to be the one I was testing with and noticed that my code couldn't expand the %s in "AE%sT". Am I missing something that says to use "S" as the LETTER/S field for dates prior to the first DST transition in 1917? What logic do other C libraries use to get "AEST" here?

6 20

Does Egypt spring forward tomorrow at 00:01 not 00:00?
by Paul Eggert April 25, 2024

April 25, 2024

Two recent news reports say that Egyptian clocks spring forward tomorrow at 00:01, not at 00:00 as per TZDB. Both cite Law No. 24 of 2023. Does anybody on this list have access to the text of that Egyptian law? I am unable to find a copy of that law online; <https://guides.loc.gov/law-egypt/legislative> points me at <https://www.egypt.gov.eg/english/laws/default.aspx> but www.egypt.gov.eg (41.33.95.166) is inaccessible to me (no packets seem to get through). I am mildly inclined to think that the distinction between 00:00 and 00:01 is being done by the news sources in question and not by the actual law. However, if someone can get a copy of the legislation that should be definitive. Here are the two sources giving spring-forward and fall-back times that differ by one minute from TZDB: * Egypt prepares to implement daylight saving time last Friday of April, Egypt Today, 2024-04-22 <https://www.egypttoday.com/Article/1/131747/Egypt-prepares-to-implement-day…> "... the current time used will be advanced by sixty minutes, starting at 12 midnight (00:01 a.m.) on Friday, April 26, until the end of the last Thursday of October at (23:59 p.m.)." * Belal Nawar, Daylight Savings in Egypt Starts on 26 April, Egyptian Streets, 2024-04-25 <https://egyptianstreets.com/2024/04/25/daylight-savings-in-egypt-starts-on-…> "The clock will be advanced by sixty minutes, starting from midnight (00:01 a.m.) on Friday 26 April, and will revert to standard time at the end of the last Thursday of October, precisely at 11:59 p.m. (23:59 p.m.)." I also see a couple of reports that we were one minute off in fall 2023: * Shereif Barakat, Egypt Bids Farewell to Daylight-Saving Time Tomorrow, Egyptian Streets, 2023-10-25 <https://egyptianstreets.com/2023/10/25/egypt-bids-farewell-to-daylight-savi…>. * Daylight Saving Time in Egypt Will End One Minute Before October 27th Scene Now, 2023-10-26 <https://scenenow.com/Buzz/Daylight-Saving-Time-in-Egypt-Will-End-One-Minute…>. On the other hand, other sources simply give transitions on the hour or on the day. Examples include <https://english.ahram.org.eg/NewsContentP/1/522092/Egypt/Summer-Time-vs-pow…> and <https://cairoscene.com/Buzz/Daylight-Saving-Time-to-Start-in-Egypt-on-Frida…>. In particular <https://www.lexology.com/library/detail.aspx?g=34fe8046-f02b-4af1-a515-30cd…>, in which an Egyptian law firm summarizes Law No. 24 (issued 16 April 2023), merely gives day boundaries. So perhaps the 00:01 and 23:59 business is merely the news sources' trying to avoid confusion.

1 0

Asia/Gaza POSIX TZ string problem
by Z Meng Chen April 22, 2024

April 22, 2024

Hi, We obtained the *tzdata2024a* from IANA. Below is the Rule for *Asia/Gaza* extracted from *tzdata2024a*: * ...* *Rule Palestine 2022 2035 - Oct Sat<=30 2:00 0 -* *Rule Palestine 2023 only - Apr 29 2:00 1:00 S* *Rule Palestine 2024 only - Apr 20 2:00 1:00 S* *Rule Palestine 2025 only - Apr 12 2:00 1:00 S* ... *Asia/Gaza POSIX TZ string (generated by zic)*: EET-2EEST, M3.4.4/50,M10.4.4/50" The rule specifies that DST in 2024 starts on April 20th. Why then does the POSIX TZ string use M3.4.4? Is this a bug? or is there any other reason? Thanks. Best regards, Meng Chen

3 5

request to update DST info for Timezone: Tehran/Iran
by Vajihe Bitarafan April 16, 2024

April 16, 2024

Hi Dear IANA, I am using some system and I encountered that in some situations Daylight Saving Time is not working correctly. >From 20 March 2023 , DST has been removed from government Policies and So from then there would not be any changes in Time. So Time zone Tehran/IRAN is +3:30 for all days of the year. I hope it will be reflected in timezone databases and I can see the Joda time is updated respectively. Thanks in advance for your help Best regards, Vajiheh Bitarafan

4 4

Vadsø, Norway mayor wants 26-hour days
by Paul Eggert April 15, 2024

April 15, 2024

On March 20 Wenche Pedersen, the mayor of Vadsø municipality, Norway, asked[1] the European Commission to issue a directive allowing Norway to create a separate time zone for the northern part of Norway. Days in the new time zone would contain 26 hours instead of the usual 24. This request is part of the "MOREtime" project. Mayor Pedersen wrote: > ... we aim to celebrate and promote this unique way of life, offering individuals the opportunity to enjoy more quality time engaging in activities such as fishing, hunting, learning new languages, or simply being with loved ones. By having our own certified time zone within the EU, we hope to attract more young people, not only from Norway but also from around the world, to discover and settle in this adventurous area. Recently the mayor's proposal has been covered by several major news organizations. When asked how the 26-hour day would actually work, the mayor replied "We haven't thought a lot about that. The clock will go from 12 to 13 ... and we have to see how this will go. I don't think they're going to say yes so we haven't thought about all the details."[2] Longtime readers of the time zone mailing list might remember that in 2019 a resident of Sommarøy, Norway petitioned his parliamentarian to abolish civil time in his town, something that also made the news.[3] However, the Sommarøy proposal was by a private individual and was easily implementable via tzdata by creating a new UTC or LMT zone with abbreviation "-00" or "LMT", whereas the Vadsø proposal is by the mayor, and would require changes to tzcode and would therefore be considerably harder to support. Although it's unlikely that the Vadsø proposal will go anywhere, it's helpful to think of how timekeeping changes like this might be accommodated by the TZDB project, as similar proposals might happen in the future. I see several ways to implement 26-hour days, falling into two major categories. Category I: Shorten civil-time hours so that there are 26 civil-time hours in a standard-length (SI) day. Four possible ways to do this are: A. Civil-time seconds are 12/13 s (i.e., 12/13 of an SI second, or about 0.923 s), so that civil-time minutes and hours are both 12/13 of their SI counterparts. B. Civil-time seconds are the same as before, but civil-time minutes are 60 * 12/13 s (i.e., about 55.38 s). C. Civil-time seconds and minutes are the same as before, but civil-time hours are 60 * 12/13 min (i.e., about 55.38 SI minutes). D. Civil-time minutes are 60 * sqrt(12/13) s (about 57.65 s), and civil-time hours are 60 * sqrt(12/13) civil-time minutes (i.e., about 57.65 civil-time minutes). Category II: Adjust day lengths so that all or most days contain 26 SI hours. Three possibilities here are: E. Civil-time days are 26 SI hours, and the calendar gradually falls further and further behind the Gregorian calendar. F. Civil-time days are 26 SI hours, but skip every 13th day so that days stay roughly synchronized with the Gregorian calendar. G. At the end of every day, move clocks backward two hours, from 24:00 to 22:00, so that timestamps from 22:00:00 through 23:59:59 repeat. Do this consistently for eleven days, thus moving clocks backward a total of 22 hours. On the twelfth day move clocks forward 22 hours instead, from 24:00 to 22:00 the next day. Repeat this cycle indefinitely. This way, eleven days out of thirteen contain 26 hours, and the next two days combined also contain 26 hours - 24 hours in the twelfth day and 2 hours in the thirteenth. Of these methods something like (G) would be the most compatible with computerized timekeeping, as (G) conforms to POSIX-1.202x Draft 4.1[4] whereas (A) through (F) do not. (G) avoids timestamps like 25:30; G's hours, minutes or seconds are all of the usual lengths; and (G) contains only transitions that are like daylight-saving transitions that computerized timekeeping can already deal with. Although a downside of (G) is that at times the sun will be at its zenith at midnight, I assume Vadsø residents are already accustomed to midnight suns so this disadvantage is relatively minor for them. Another downside of (G) is that clocks will never go "from 12 to 13" as the mayor requested, but given the major technical difficulties of (A) through (F) I hope the mayor would appreciate that (G) may be the best we can practically hope for in today's standardized and computerized world. Unfortunately even (G) would require some changes to tzcode and tzdata to become practical, and it would take many years for these changes to propagate to devices in common use in Vadsø. So, unless Vadsø residents are prepared to change their clocks by hand every day for the next several years, it does not appear that the mayor's proposal will be practical any time soon. I am sending this email to the time zone mailing list, as perhaps someone on the list can think of even better ways to implement the mayor's request. I am also cc'ing this email to Mayor Pedersen to give her a heads-up about this analysis, should it ever be needed in Vadsø. [1]: https://kommunikasjon.ntb.no/files/17848798/18066114/57109/no [2]: https://www.politico.eu/article/norway-arctic-region-asks-eu-commission-for… [3]: https://mm.icann.org/pipermail/tz/2019-June/028154.html [4]: https://www.opengroup.org/austin/

6 5

Kazakhstan Airline Schedules
by Owen Leibman April 14, 2024

April 14, 2024

I have a friend in Kazakhstan whom, thanks to this list, I notified about the recent time change before it was widely known in the country. She says the transition was pretty smooth, but, over a month later, sent me a message, which I pass on (without the attachments showing the discrepancies) as an anecdotal demonstration of how hard it is to get all the pieces in place: Happy eclipse day! I'm sending an update for your friends on time zones and flights. I booked a flight in February to Frankfurt leaving this Wednesday. United says the flight departs 4:20 a.m., but Lufthansa sent me an email saying I could check in for my flight which leaves at 3:20 a.m. Yet another Lufthansa check-in screen and the boarding pass says it leaves at 4:20. Meanwhile FlightAware claims the flight is not leaving till 5:20 a.m. All have the same arrival time of 9 a.m. Nursultan airport website does not list the flight yet. I will let you know which one proves to be right! I think it's 4:20. This email and any files transmitted with it are confidential, proprietary and intended solely for the individual or entity to whom they are addressed. If you have received this email in error please delete it immediately.

2 3

[PROPOSED] Shanks is likely wrong about Maputo switch to CAT
by Paul Eggert April 9, 2024

April 9, 2024

* NEWS: Mention the change, and leave room for future Portugal fixes. * africa (Africa/Maputo): Tweak LMT to match London Gazette, and change CAT transition date to a guess of 1909. --- NEWS | 4 ++++ africa | 19 ++++++++++++++----- 2 files changed, 18 insertions(+), 5 deletions(-) diff --git a/NEWS b/NEWS index 25d939f1..0d6a1513 100644 --- a/NEWS +++ b/NEWS @@ -4,6 +4,7 @@ Unreleased, experimental changes Briefly: The main data form now uses %z. + Improve historical data for Portugal and possessions. Changes to data @@ -15,6 +16,9 @@ Unreleased, experimental changes the represented data: the generated TZif files are unchanged. Rearguard form still avoids %z, to support obsolescent parsers. + Some transitions for Portugal and possessions have been changed. + This affects timestamps for Africa/Maputo before 1909. + Asia/Almaty has been removed from zonenow.tab as it now agrees with Asia/Tashkent for future timestamps, due to Kazakhstan's 2024-02-29 time zone change. Similarly, America/Scoresbysund diff --git a/africa b/africa index a731dbee..695d66ed 100644 --- a/africa +++ b/africa @@ -1101,13 +1101,22 @@ Zone Africa/El_Aaiun -0:52:48 - LMT 1934 Jan # El Aaiún # Zambia # Zimbabwe # -# Shanks gives 1903-03-01 for the transition to CAT. -# Perhaps the 1911-05-26 Portuguese decree -# https://dre.pt/pdf1sdip/1911/05/12500/23132313.pdf -# merely made it official? +# From Paul Eggert (2024-04-09): +# The London Gazette, 1903-04-03, page 2245, says that +# as of 1903-03-03 a time ball at the port of Lourenço Marques +# (as Maputo was then called) was dropped daily at 13:00:00 LMT, +# corresponding to 22:49:41.7 GMT; round this to UT+2:10:18. +# Conversely, the newspaper South Africa, 1909-02-09, page 321, +# says the port had just installed an apparatus that communicated +# "from the controlling clock in the new Observatory at Reuben Point ... +# exact mean South African time, i.e., 30 deg., or 2 hours East of Greenwich". +# Although Shanks gives 1903-03-01 for the transition to CAT, +# evidently the port transitioned to CAT after 1903-03-03 but before +# the Portuguese legal transition of 1912-01-01 (see Europe/Lisbon commentary). +# For lack of better info, list 1909 as the transition date. # # Zone NAME STDOFF RULES FORMAT [UNTIL] -Zone Africa/Maputo 2:10:20 - LMT 1903 Mar +Zone Africa/Maputo 2:10:18 - LMT 1909 2:00 - CAT # Namibia -- 2.44.0

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Using %z in FORMAT column of 'europe' etc.
by Paul Eggert April 8, 2024

April 8, 2024

[This is a repost with minor updates of <https://mm.icann.org/pipermail/tz/2024-March/058790.html>. This repost is in a separate email thread, with a clearer "Subject:" line.] The recent glitches with %z-related lines in the Portugal data lead me to think that it's time to start using %z in the main format. For example, instead of this: > # Zone NAME STDOFF RULES FORMAT [UNTIL] > Zone Atlantic/Azores -1:42:40 - LMT 1884 # Ponta Delgada > -1:54:32 - HMT 1912 Jan 1 2:00u # Horta MT > -2:00 Port -02/-01 1942 Apr 25 22:00s > -2:00 Port +00 1942 Aug 15 22:00s > -2:00 Port -02/-01 1943 Apr 17 22:00s > -2:00 Port +00 1943 Aug 28 22:00s > -2:00 Port -02/-01 1944 Apr 22 22:00s > -2:00 Port +00 1944 Aug 26 22:00s > -2:00 Port -02/-01 1945 Apr 21 22:00s > -2:00 Port +00 1945 Aug 25 22:00s > -2:00 Port -02/-01 1966 Apr 3 2:00 > -1:00 Port -01/+00 1983 Sep 25 1:00s > -1:00 W-Eur -01/+00 1992 Sep 27 1:00s the 'europe' file should contain this: > # Zone NAME STDOFF RULES FORMAT [UNTIL] > Zone Atlantic/Azores -1:42:40 - LMT 1884 # Ponta Delgada > -1:54:32 - HMT 1912 Jan 1 2:00u # Horta MT > -2:00 Port %z 1966 Apr 3 2:00 > -1:00 Port %z 1983 Sep 25 1:00s > -1:00 W-Eur %z 1992 Sep 27 1:00s This would eventually simplify future maintenance and help avoid similar glitches in the future. For now, the 'rearguard' format would continue to avoid %z in the FORMAT column. It's reasonable to use %z in 'europe' now, as zic has supported %z since release 2015f.

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