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Show All 20 Lines | </p> | ||||
<h3>Outline</h3> | <h3>Outline</h3> | ||||
<nav> | <nav> | ||||
<ul> | <ul> | ||||
<li>The <code><abbr>tz</abbr></code> database product and process | <li>The <code><abbr>tz</abbr></code> database product and process | ||||
<ul> | <ul> | ||||
<li><a href="#tzdb">The <code><abbr>tz</abbr></code> database</a></li> | <li><a href="#tzdb">The <code><abbr>tz</abbr></code> database</a></li> | ||||
<li><a href="#download">Downloading the <code><abbr>tz</abbr></code> database</a></li> | <li><a href="#download">Downloading the <code><abbr>tz</abbr></code> database</a></li> | ||||
<li><a href="#changes">Changes to the <code><abbr>tz</abbr></code> database</a></li> | <li><a href="#changes">Changes to the <code><abbr>tz</abbr></code> database</a></li> | ||||
<li><a href="#coordinating">Coordinating with governments and distributors</a></li> | |||||
<li><a href="#commentary">Commentary on the <code><abbr>tz</abbr></code> database</a></li> | <li><a href="#commentary">Commentary on the <code><abbr>tz</abbr></code> database</a></li> | ||||
</ul> | </ul> | ||||
</li> | </li> | ||||
<li>Uses of the <code><abbr>tz</abbr></code> database | <li>Uses of the <code><abbr>tz</abbr></code> database | ||||
<ul> | <ul> | ||||
<li><a href="#web">Web sites using recent versions of the <code><abbr>tz</abbr></code> database</a></li> | <li><a href="#web">Web sites using recent versions of the <code><abbr>tz</abbr></code> database</a></li> | ||||
<li><a href="#protocols">Network protocols for <code><abbr>tz</abbr></code> data</a></li> | <li><a href="#protocols">Network protocols for <code><abbr>tz</abbr></code> data</a></li> | ||||
<li><a href="#compilers">Other <code><abbr>tz</abbr></code> compilers</a></li> | <li><a href="#compilers">Other <code><abbr>tz</abbr></code> compilers</a></li> | ||||
▲ Show 20 Lines • Show All 127 Lines • ▼ Show 20 Lines | |||||
where <code><var>V</var></code> is the version. | where <code><var>V</var></code> is the version. | ||||
Since 1996, each version has been a four-digit year followed by | Since 1996, each version has been a four-digit year followed by | ||||
lower-case letter (<samp>a</samp> through <samp>z</samp>, | lower-case letter (<samp>a</samp> through <samp>z</samp>, | ||||
then <samp>za</samp> through <samp>zz</samp>, then <samp>zza</samp> | then <samp>za</samp> through <samp>zz</samp>, then <samp>zza</samp> | ||||
through <samp>zzz</samp>, and so on). | through <samp>zzz</samp>, and so on). | ||||
Since version 2022a, each release has been distributed in | Since version 2022a, each release has been distributed in | ||||
<a href="https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06">POSIX | <a href="https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06">POSIX | ||||
ustar interchange format</a>, compressed as described above; | ustar interchange format</a>, compressed as described above; | ||||
older releases use a nearly-compatible format. | older releases use a nearly compatible format. | ||||
Since version 2016h, each release has contained a text file named | Since version 2016h, each release has contained a text file named | ||||
"<samp>version</samp>" whose first (and currently only) line is the version. | "<samp>version</samp>" whose first (and currently only) line is the version. | ||||
Older releases are <a href="https://ftp.iana.org/tz/releases/">archived</a>, | Older releases are <a href="https://ftp.iana.org/tz/releases/">archived</a>, | ||||
and are also available in an | and are also available in an | ||||
<a href="ftp://ftp.iana.org/tz/releases/"><abbr | <a href="ftp://ftp.iana.org/tz/releases/"><abbr | ||||
title="File Transfer Protocol">FTP</abbr> directory</a> via a | title="File Transfer Protocol">FTP</abbr> directory</a> via a | ||||
less-secure protocol.</p> | less secure protocol.</p> | ||||
<p>Alternatively, a development repository of code and data can be | <p>Alternatively, a development repository of code and data can be | ||||
retrieved from <a href="https://github.com">GitHub</a> via the shell | retrieved from <a href="https://github.com">GitHub</a> via the shell | ||||
command:</p> | command:</p> | ||||
<pre><code><a href="https://git-scm.com">git</a> clone <a href="https://github.com/eggert/tz">https://github.com/eggert/tz</a> | <pre><code><a href="https://git-scm.com">git</a> clone <a href="https://github.com/eggert/tz">https://github.com/eggert/tz</a> | ||||
</code></pre> | </code></pre> | ||||
<p> | <p> | ||||
Since version 2012e, each release has been tagged in development repositories. | Since version 2012e, each release has been tagged in development repositories. | ||||
Untagged commits are less well tested and probably contain | Untagged commits are less well tested and probably contain | ||||
Show All 22 Lines | |||||
and browse the <a | and browse the <a | ||||
href="https://mm.icann.org/pipermail/tz/">archive of old | href="https://mm.icann.org/pipermail/tz/">archive of old | ||||
messages</a>. | 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 | discussions</a> and corresponding data changes can be | ||||
generated <a href="https://github.com/timparenti/tzdata-meta">automatically</a>. | generated <a href="https://github.com/timparenti/tzdata-meta">automatically</a>. | ||||
</p> | </p> | ||||
<p> | <p> | ||||
If your government plans to change its time zone boundaries or | |||||
daylight saving rules, inform <code>tz@iana.org</code> well in | |||||
advance, as this will coordinate updates to many cell phones, | |||||
computers, and other devices around the world. | |||||
The change should be officially announced at least a year before it affects | |||||
how clocks operate; otherwise, there is a good chance that some | |||||
clocks will operate incorrectly after the change, due | |||||
to delays in propagating updates to software and data. The shorter | |||||
the notice, the more likely clock problems will arise; see "<a | |||||
href="https://codeofmatt.com/2016/04/23/on-the-timing-of-time-zone-changes/">On | |||||
the Timing of Time Zone Changes</a>" for examples. | |||||
The <code><abbr>tz</abbr></code> data can represent planned changes | |||||
far into the future, and a long-planned change can easily be reverted | |||||
or otherwise altered with a year's notice before the change would have | |||||
affected clocks. | |||||
</p> | |||||
<p> | |||||
Changes to the <code><abbr>tz</abbr></code> code and data are often | Changes to the <code><abbr>tz</abbr></code> code and data are often | ||||
propagated to clients via operating system updates, so | propagated to clients via operating system updates, so | ||||
client <code><abbr>tz</abbr></code> data can often be corrected by | client <code><abbr>tz</abbr></code> data can often be corrected by | ||||
applying these updates. With GNU/Linux and similar systems, if your | applying these updates. With GNU/Linux and similar systems, if your | ||||
maintenance provider has not yet adopted the | maintenance provider has not yet adopted the | ||||
latest <code><abbr>tz</abbr></code> data, you can often short-circuit | latest <code><abbr>tz</abbr></code> data, you can often short-circuit | ||||
the process by tailoring the generic instructions in | the process by tailoring the generic instructions in | ||||
the <code><abbr>tz</abbr> README</code> file and installing the latest | the <code><abbr>tz</abbr> README</code> file and installing the latest | ||||
Show All 39 Lines | |||||
found in <a href="theory.html">Theory and pragmatics of the | found in <a href="theory.html">Theory and pragmatics of the | ||||
<code><abbr>tz</abbr></code> code and data</a>. | <code><abbr>tz</abbr></code> code and data</a>. | ||||
<a href="https://a0.github.io/a0-tzmigration/">A0 TimeZone Migration</a> | <a href="https://a0.github.io/a0-tzmigration/">A0 TimeZone Migration</a> | ||||
displays changes between recent <code><abbr>tzdb</abbr></code> versions. | displays changes between recent <code><abbr>tzdb</abbr></code> versions. | ||||
</p> | </p> | ||||
</section> | </section> | ||||
<section> | <section> | ||||
<h2 id="coordinating">Coordinating with governments and distributors</h2> | |||||
<p> | |||||
As discussed in | |||||
"<a href="https://www.icann.org/en/blogs/details/how-time-zones-are-coordinated-13-03-2023-en">How | |||||
Time Zones Are Coordinated</a>", the time zone database relies on | |||||
collaboration among governments, the time zone database volunteer | |||||
community, and data distributors downstream. | |||||
<p> | |||||
If your government plans to change its time zone boundaries or | |||||
daylight saving rules, please send email to <a | |||||
href="mailto:tz@iana.org"><code>tz@iana.org</code></a> well in advance, | |||||
as this will lessen confusion and will coordinate updates to many cell phones, | |||||
computers, and other devices around the world. | |||||
In your email, please cite the legislation or regulation that specifies | |||||
the change, so that it can be checked for details such as the exact times | |||||
when clock transitions occur. | |||||
It is OK if a rule change is planned to affect clocks | |||||
far into the future, as a long-planned change can easily be reverted | |||||
or otherwise altered with a year's notice before the change would have | |||||
affected clocks.</p> | |||||
<p> | |||||
There is no fixed schedule for <code><abbr>tzdb</abbr></code> releases. | |||||
However, typically a release occurs every few months. | |||||
Many downstream timezone data distributors wait for | |||||
a <code><abbr>tzdb</abbr></code> release before they produce an update | |||||
to time zone behavior in consumer devices and software products. | |||||
After a release, various parties must integrate, test, | |||||
and roll out an update before <a | |||||
href="https://en.wikipedia.org/wiki/End_user">end users</a> see changes. | |||||
These updates can be expensive, for both the <a | |||||
href="https://en.wikipedia.org/wiki/Quality_assurance">quality | |||||
assurance</a> process and the overall cost of shipping and installing | |||||
updates to each device's copy of <code><abbr>tzdb</abbr></code>. | |||||
Updates may be batched with other updates and may take substantial | |||||
time to reach end users after a release. | |||||
Older devices may no longer be supported and thus may never be updated, | |||||
which means they will continue to use out-of-date rules.</p> | |||||
<p> | |||||
For these reasons any rule change should be promulgated at least a | |||||
year before it affects how clocks operate; otherwise, there is a good | |||||
chance that many clocks will be wrong due to delays in propagating updates, | |||||
and that residents will be confused or even actively resist the change. | |||||
The shorter the notice, the more likely clock problems will arise; see "<a | |||||
href="https://codeofmatt.com/2016/04/23/on-the-timing-of-time-zone-changes/">On | |||||
the Timing of Time Zone Changes</a>" for examples. | |||||
</p> | |||||
</section> | |||||
<section> | |||||
<h2 id="commentary">Commentary on the <code><abbr>tz</abbr></code> database</h2> | <h2 id="commentary">Commentary on the <code><abbr>tz</abbr></code> database</h2> | ||||
<ul> | <ul> | ||||
<li>The article | <li>The article | ||||
<a href="https://en.wikipedia.org/wiki/Tz_database">tz database</a> is | <a href="https://en.wikipedia.org/wiki/Tz_database">tz database</a> is | ||||
an encyclopedic summary.</li> | an encyclopedic summary.</li> | ||||
<li><a href="tz-how-to.html">How to Read the | <li><a href="tz-how-to.html">How to Read the | ||||
tz Database Source Files</a> explains the <code><abbr>tz</abbr></code> | tz Database Source Files</a> explains the <code><abbr>tz</abbr></code> | ||||
database format.</li> | database format.</li> | ||||
▲ Show 20 Lines • Show All 81 Lines • ▼ Show 20 Lines | |||||
<h2 id="compilers">Other <code><abbr>tz</abbr></code> compilers</h2> | <h2 id="compilers">Other <code><abbr>tz</abbr></code> compilers</h2> | ||||
<p>Although some of these do not fully support | <p>Although some of these do not fully support | ||||
<code><abbr>tz</abbr></code> data, in recent <code><abbr>tzdb</abbr></code> | <code><abbr>tz</abbr></code> data, in recent <code><abbr>tzdb</abbr></code> | ||||
distributions you can generally work around compatibility problems by | distributions you can generally work around compatibility problems by | ||||
running the command <code>make rearguard_tarballs</code> and compiling | running the command <code>make rearguard_tarballs</code> and compiling | ||||
from the resulting tarballs instead.</p> | from the resulting tarballs instead.</p> | ||||
<ul> | <ul> | ||||
<li><a href="https://sourceforge.net/projects/vzic/">Vzic</a> is a <a | <li><a href="https://sourceforge.net/projects/vzic/">Vzic</a> is a <a | ||||
href="https://en.wikipedia.org/wiki/C_%28programming_language%29">C</a> | href="https://en.wikipedia.org/wiki/C_(programming_language)">C</a> | ||||
program that compiles | program that compiles | ||||
<code><abbr>tz</abbr></code> source into iCalendar-compatible VTIMEZONE files. | <code><abbr>tz</abbr></code> source into iCalendar-compatible VTIMEZONE files. | ||||
Vzic is freely | Vzic is freely | ||||
available under the <a | available under the <a | ||||
href="https://www.gnu.org/copyleft/gpl.html"><abbr>GNU</abbr> | href="https://www.gnu.org/copyleft/gpl.html"><abbr>GNU</abbr> | ||||
General Public License (<abbr | General Public License (<abbr | ||||
title="General Public License">GPL</abbr>)</a>.</li> | title="General Public License">GPL</abbr>)</a>.</li> | ||||
<li><a href="https://sourceforge.net/projects/tzical/">tziCal – tz | <li><a href="https://sourceforge.net/projects/tzical/">tziCal – tz | ||||
database conversion utility</a> is like Vzic, except for the <a | database conversion utility</a> is like Vzic, except for the <a | ||||
href="https://dotnet.microsoft.com">.NET framework</a> | href="https://dotnet.microsoft.com">.NET framework</a> | ||||
and with a <abbr>BSD</abbr>-style license.</li> | and with a <abbr>BSD</abbr>-style license.</li> | ||||
<li><a | <li><a | ||||
href="https://metacpan.org/release/DateTime-TimeZone">DateTime::TimeZone</a> | href="https://metacpan.org/release/DateTime-TimeZone">DateTime::TimeZone</a> | ||||
contains a script <code>parse_olson</code> that compiles | contains a script <code>parse_olson</code> that compiles | ||||
<code><abbr>tz</abbr></code> source into <a href="https://www.perl.org">Perl</a> | <code><abbr>tz</abbr></code> source into <a href="https://www.perl.org">Perl</a> | ||||
modules. It is part of the Perl <a | modules. It is part of the Perl <a | ||||
href="https://github.com/houseabsolute/DateTime.pm/wiki">DateTime Project</a>, | href="https://github.com/houseabsolute/DateTime.pm/wiki">DateTime Project</a>, | ||||
which is freely | which is freely | ||||
available under both the <abbr>GPL</abbr> and the Perl Artistic | available under both the <abbr>GPL</abbr> and the Perl Artistic | ||||
License. DateTime::TimeZone also contains a script | License. DateTime::TimeZone also contains a script | ||||
<code>tests_from_zdump</code> that generates test cases for each clock | <code>tests_from_zdump</code> that generates test cases for each clock | ||||
transition in the <code><abbr>tz</abbr></code> database.</li> | transition in the <code><abbr>tz</abbr></code> database.</li> | ||||
<li>The <a href="https://howardhinnant.github.io/date/tz.html">Time Zone | <li>The <a href="https://howardhinnant.github.io/date/tz.html">Time Zone | ||||
Database Parser</a> is a | Database Parser</a> is a | ||||
<a href="https://en.wikipedia.org/wiki/C%2B%2B">C++</a> parser and | <a href="https://en.wikipedia.org/wiki/C++">C++</a> parser and | ||||
runtime library with <a | runtime library with <a | ||||
href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0355r7.html">API</a> | href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0355r7.html">API</a> | ||||
adopted by | adopted by | ||||
<a href="https://en.wikipedia.org/wiki/C++20">C++20</a>, | <a href="https://en.wikipedia.org/wiki/C++20">C++20</a>, | ||||
the current iteration of the C++ standard. | the current iteration of the C++ standard. | ||||
It is freely available under the | It is freely available under the | ||||
<abbr title="Massachusetts Institute of Technology">MIT</abbr> license.</li> | <abbr title="Massachusetts Institute of Technology">MIT</abbr> license.</li> | ||||
<li><a id="ICU" href="https://icu.unicode.org">International Components for | <li><a id="ICU" href="https://icu.unicode.org">International Components for | ||||
Unicode (<abbr>ICU</abbr>)</a> contains C/C++ and <a | Unicode (<abbr>ICU</abbr>)</a> contains C/C++ and <a | ||||
href="https://en.wikipedia.org/wiki/Java_%28programming_language%29">Java</a> | href="https://en.wikipedia.org/wiki/Java_(programming_language)">Java</a> | ||||
libraries for internationalization that | libraries for internationalization that | ||||
has a compiler from <code><abbr>tz</abbr></code> source | has a compiler from <code><abbr>tz</abbr></code> source | ||||
and from <abbr title="Common Locale Data Repository">CLDR</abbr> data | and from <abbr title="Common Locale Data Repository">CLDR</abbr> data | ||||
(mentioned <a href="#CLDR">below</a>) | (mentioned <a href="#CLDR">below</a>) | ||||
into an <abbr>ICU</abbr>-specific format. | into an <abbr>ICU</abbr>-specific format. | ||||
<abbr>ICU</abbr> is freely available under a | <abbr>ICU</abbr> is freely available under a | ||||
<abbr>BSD</abbr>-style license.</li> | <abbr>BSD</abbr>-style license.</li> | ||||
<li>The <a href="https://github.com/lau/tzdata">Tzdata</a> package for | <li>The <a href="https://github.com/lau/tzdata">Tzdata</a> package for | ||||
▲ Show 20 Lines • Show All 467 Lines • ▼ Show 20 Lines | |||||
<dt>Netherlands</dt> | <dt>Netherlands</dt> | ||||
<dd><a href="https://www.staff.science.uu.nl/~gent0113/wettijd/wettijd.htm" | <dd><a href="https://www.staff.science.uu.nl/~gent0113/wettijd/wettijd.htm" | ||||
hreflang="nl">Legal time in the Netherlands (in Dutch)</a> | hreflang="nl">Legal time in the Netherlands (in Dutch)</a> | ||||
covers the history of local time in the Netherlands from ancient times.</dd> | covers the history of local time in the Netherlands from ancient times.</dd> | ||||
<dt>New Zealand</dt> | <dt>New Zealand</dt> | ||||
<dd>The Department of Internal Affairs maintains a brief <a | <dd>The Department of Internal Affairs maintains a brief <a | ||||
href="https://www.dia.govt.nz/Daylight-Saving-History">History of | href="https://www.dia.govt.nz/Daylight-Saving-History">History of | ||||
Daylight Saving</a>.</dd> | Daylight Saving</a>.</dd> | ||||
<dt>Palestine</dt> | |||||
<dd>The Ministry of Telecom and IT publishes a <a | |||||
href="https://mtit.pna.ps/Site/TimeZoon" | |||||
hreflang="ar">history of clock changes (in Arabic)</a>.</dd> | |||||
<dt>Portugal</dt> | <dt>Portugal</dt> | ||||
<dd>The Lisbon Astronomical Observatory publishes a | <dd>The Lisbon Astronomical Observatory publishes a | ||||
<a href="https://oal.ul.pt/hora-legal/" hreflang="pt">history of | <a href="https://oal.ul.pt/hora-legal/" hreflang="pt">history of | ||||
legal time (in Portuguese)</a>.</dd> | legal time (in Portuguese)</a>.</dd> | ||||
<dt>Singapore</dt> | <dt>Singapore</dt> | ||||
<dd><a id="Singapore" | <dd><a id="Singapore" | ||||
href="https://web.archive.org/web/20190822231045/http://www.math.nus.edu.sg/~mathelmr/teaching/timezone.html">Why | href="https://web.archive.org/web/20190822231045/http://www.math.nus.edu.sg/~mathelmr/teaching/timezone.html">Why | ||||
is Singapore in the "Wrong" Time Zone?</a> details the | is Singapore in the "Wrong" Time Zone?</a> details the | ||||
▲ Show 20 Lines • Show All 59 Lines • ▼ Show 20 Lines | |||||
<section> | <section> | ||||
<h2 id="precision">Precision timekeeping</h2> | <h2 id="precision">Precision timekeeping</h2> | ||||
<ul> | <ul> | ||||
<li><a | <li><a | ||||
href="http://leapsecond.com/hpan/an1289.pdf">The | href="http://leapsecond.com/hpan/an1289.pdf">The | ||||
Science of Timekeeping</a> is a thorough introduction | Science of Timekeeping</a> is a thorough introduction | ||||
to the theory and practice of precision timekeeping.</li> | to the theory and practice of precision timekeeping.</li> | ||||
<li><a href="https://doi.org/10.1007/978-3-319-59909-0">The Science of | <li><a href="https://doi.org/10.1007/978-3-319-59909-0">The Science of | ||||
Time 2016</a> contains several freely-readable papers.</li> | Time 2016</a> contains several freely readable papers.</li> | ||||
<li><a href="https://www.ntp.org"><abbr | <li><a href="https://www.ntp.org"><abbr | ||||
title="Network Time Protocol">NTP</abbr>: The Network | title="Network Time Protocol">NTP</abbr>: The Network | ||||
Time Protocol</a> (Internet <abbr>RFC</abbr> 5905) | Time Protocol</a> (Internet <abbr>RFC</abbr> 5905) | ||||
discusses how to synchronize clocks of | discusses how to synchronize clocks of | ||||
Internet hosts.</li> | Internet hosts.</li> | ||||
<li>The <a href="https://www.usenix.org/system/files/conference/nsdi18/nsdi18-geng.pdf"><span style="font-variant: small-caps">Huygens</span></a> | <li>The <a href="https://www.usenix.org/system/files/conference/nsdi18/nsdi18-geng.pdf"><span style="font-variant: small-caps">Huygens</span></a> | ||||
family of software algorithms can achieve accuracy to a few tens of | family of software algorithms can achieve accuracy to a few tens of | ||||
nanoseconds in scalable server farms without special hardware.</li> | nanoseconds in scalable server farms without special hardware.</li> | ||||
▲ Show 20 Lines • Show All 55 Lines • ▼ Show 20 Lines | |||||
timestamps starting with <code>time_t</code> 78 796 800, | timestamps starting with <code>time_t</code> 78 796 800, | ||||
which corresponds to the first leap second | which corresponds to the first leap second | ||||
1972-06-30 23:59:60 <abbr>UTC</abbr> in the "<code>right</code>" configuration, | 1972-06-30 23:59:60 <abbr>UTC</abbr> in the "<code>right</code>" configuration, | ||||
and to | and to | ||||
1972-07-01 00:00:00 <abbr>UTC</abbr> in the "<code>posix</code>" configuration. | 1972-07-01 00:00:00 <abbr>UTC</abbr> in the "<code>posix</code>" configuration. | ||||
In practice the two configurations also agree for timestamps before | In practice the two configurations also agree for timestamps before | ||||
1972 even though the historical situation is messy, partly because | 1972 even though the historical situation is messy, partly because | ||||
neither <abbr>UTC</abbr> nor <abbr>TAI</abbr> | neither <abbr>UTC</abbr> nor <abbr>TAI</abbr> | ||||
is well-defined for sufficiently-old timestamps.</li> | is well-defined for sufficiently old timestamps.</li> | ||||
<li><a href="https://developers.google.com/time/smear">Leap Smear</a> | <li><a href="https://developers.google.com/time/smear">Leap Smear</a> | ||||
discusses how to gradually adjust <abbr>POSIX</abbr> clocks near a | discusses how to gradually adjust <abbr>POSIX</abbr> clocks near a | ||||
leap second so that they disagree with <abbr>UTC</abbr> by at most a | leap second so that they disagree with <abbr>UTC</abbr> by at most a | ||||
half second, even though every <abbr>POSIX</abbr> minute has exactly | half second, even though every <abbr>POSIX</abbr> minute has exactly | ||||
sixty seconds. This approach works with the default <code><abbr>tz</abbr></code> | sixty seconds. This approach works with the default <code><abbr>tz</abbr></code> | ||||
"<code>posix</code>" configuration, is <a | "<code>posix</code>" configuration, is <a | ||||
href="http://bk1.ntp.org/ntp-stable/README.leapsmear">supported</a> by | href="http://bk1.ntp.org/ntp-stable/README.leapsmear">supported</a> by | ||||
the <abbr>NTP</abbr> reference implementation, <a | the <abbr>NTP</abbr> reference implementation, <a | ||||
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href="https://www2.unb.ca/gge/Resources/gpsworld.november99.pdf">McCarthy | href="https://www2.unb.ca/gge/Resources/gpsworld.november99.pdf">McCarthy | ||||
and Klepczynski's 1999 proposal to discontinue leap seconds</a>, | and Klepczynski's 1999 proposal to discontinue leap seconds</a>, | ||||
discussed further in | discussed further in | ||||
<a href="https://www.cl.cam.ac.uk/~mgk25/time/metrologia-leapsecond.pdf">The | <a href="https://www.cl.cam.ac.uk/~mgk25/time/metrologia-leapsecond.pdf">The | ||||
leap second: its history and possible future</a>. | leap second: its history and possible future</a>. | ||||
<a href="https://www.ucolick.org/~sla/leapsecs/"><abbr>UTC</abbr> | <a href="https://www.ucolick.org/~sla/leapsecs/"><abbr>UTC</abbr> | ||||
might be redefined | might be redefined | ||||
without Leap Seconds</a> gives pointers on this | without Leap Seconds</a> gives pointers on this | ||||
contentious issue, which was active until 2015 and could become active | contentious issue. | ||||
again.</li> | The General Conference on Weights and Measures | ||||
<a href="https://www.bipm.org/en/cgpm-2022/resolution-4">voted in 2022</a> | |||||
to discontinue the use of leap seconds by 2035, replacing them with an | |||||
as-yet-undetermined scheme some time after the year 2135. | |||||
</li> | |||||
</ul> | </ul> | ||||
</section> | </section> | ||||
<section> | <section> | ||||
<h2 id="notation">Time notation</h2> | <h2 id="notation">Time notation</h2> | ||||
<ul> | <ul> | ||||
<li>The <a id="CLDR" href="https://cldr.unicode.org">Unicode Common Locale Data | <li>The <a id="CLDR" href="https://cldr.unicode.org">Unicode Common Locale Data | ||||
Repository (<abbr>CLDR</abbr>) Project</a> has localizations for time | Repository (<abbr>CLDR</abbr>) Project</a> has localizations for time | ||||
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