May 2024 - tz - lists.iana.org

[PROPOSED 1/2] Don’t be so sure about leap seconds going away
by Paul Eggert May 14, 2024

May 14, 2024

* NEWS, theory.html (Leap seconds): * tz-link.html (Precision timekeeping): Use less-sure wording about leap seconds discontinuance, since the situation is still murky. --- NEWS | 2 +- theory.html | 10 +++++----- tz-link.html | 1 + 3 files changed, 7 insertions(+), 6 deletions(-) diff --git a/NEWS b/NEWS index 5c2cd1e5..e5db26b4 100644 --- a/NEWS +++ b/NEWS @@ -322,7 +322,7 @@ Release 2023a - 2023-03-22 12:39:33 -0700 To improve tzselect diagnostics, zone1970.tab's comments column is now limited to countries that have multiple timezones. - Note that leap seconds are planned to be discontinued by 2035. + Note that there are plans to discontinue leap seconds by 2035. Release 2022g - 2022-11-29 08:58:31 -0800 diff --git a/theory.html b/theory.html index 50e9ee4d..4cb293da 100644 --- a/theory.html +++ b/theory.html @@ -1278,11 +1278,11 @@ between now and the future time. <p> Leap seconds were introduced in 1972 to accommodate the difference between atomic time and the less regular rotation of the earth. -Unfortunately they caused so many problems with civil -timekeeping that they -are <a href="https://www.bipm.org/en/cgpm-2022/resolution-4">planned -to be discontinued by 2035</a>. -Despite their impending obsolescence, a record of leap seconds is still +Unfortunately they have caused so many problems with civil +timekeeping that there are +<a href="https://www.bipm.org/en/cgpm-2022/resolution-4">plans +to discontinue them by 2035</a>. +Even if these plans come to fruition, a record of leap seconds will still be needed to resolve timestamps from 1972 through 2035. </p> diff --git a/tz-link.html b/tz-link.html index c6d96101..aaab7555 100644 --- a/tz-link.html +++ b/tz-link.html @@ -1129,6 +1129,7 @@ discontinuous adjustments be made to UTC for at least a century. The World Radiocommunication Conference <a href="https://www.itu.int/dms_pub/itu-r/opb/act/R-ACT-WRC.15-2023-PDF-E.pdf">resolved in 2023</a> to cooperate with this process. +However, there is still no consensus on how exactly to get rid of them. </li> </ul> </section> -- 2.40.1

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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.

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[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?

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