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Diffstat (limited to 'tz-link.html')
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1 files changed, 150 insertions, 139 deletions
diff --git a/tz-link.html b/tz-link.html index ad2cc972a4f9..9267fb6f822b 100644 --- a/tz-link.html +++ b/tz-link.html @@ -73,7 +73,7 @@ This database (known as <code><abbr>tz</abbr></code>, is used by several implementations, including <a href="https://www.gnu.org/software/libc/">the -<abbr title="GNU's Not Unix">GNU</abbr> +<abbr title="GNU’s Not Unix">GNU</abbr> C Library</a> (used in <a href="https://en.wikipedia.org/wiki/Linux"><abbr>GNU</abbr>/Linux</a>), <a href="https://www.android.com">Android</a>, @@ -84,7 +84,6 @@ title="Berkeley Software Distribution">BSD</abbr></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>, <a href="https://musl.libc.org">musl libc</a>, <a href="https://www.mysql.com">MySQL</a>, <a href="https://en.wikipedia.org/wiki/WebOS"><abbr @@ -97,8 +96,9 @@ title="iPhone OS">iOS</abbr></a>, <a href="https://www.microsoft.com/en-us/windows">Microsoft Windows</a>, <a href="https://www.vmssoftware.com">Open<abbr title="Virtual Memory System">VMS</abbr></a>, -<a href="https://www.oracle.com/database/">Oracle Database</a>, and -<a href="https://www.oracle.com/solaris">Oracle Solaris</a>.</p> +<a href="https://www.oracle.com/database/">Oracle Database</a>, +<a href="https://www.oracle.com/solaris">Oracle Solaris</a>, +and <a href="https://blackberry.qnx.com/en">QNX</a>.</p> <p> Each main entry in the database represents a <dfn>timezone</dfn> for a set of civil-time clocks that have all agreed since 1970. @@ -117,7 +117,7 @@ To use the database on a <a href="https://en.wikipedia.org/wiki/POSIX"><abbr title="Portable Operating System Interface">POSIX</abbr>.1-2024</a> implementation set the <code><abbr>TZ</abbr></code> -environment variable to the location's full name, +environment variable to the location’s full name, e.g., <code><abbr>TZ</abbr>="America/New_York"</code>.</p> <p> Associated with each timezone is a history of offsets from @@ -138,7 +138,7 @@ for Eastern Standard Time in the <abbr>US</abbr>.</p> <p> The following <a href="https://en.wikipedia.org/wiki/Unix_shell">shell</a> commands download -the latest release's two +the latest release’s two <a href="https://en.wikipedia.org/wiki/Tar_(computing)">tarballs</a> to a <abbr>GNU</abbr>/Linux or similar host.</p> <pre><code>mkdir tzdb @@ -169,17 +169,20 @@ lower-case letter (<samp>a</samp> through <samp>z</samp>, then <samp>za</samp> through <samp>zz</samp>, then <samp>zza</samp> through <samp>zzz</samp>, and so on). 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/9799919799/utilities/pax.html#tag_20_94_13_06">POSIX ustar interchange format</a>, compressed as described above; older releases use a nearly compatible format. Since version 2016h, each release has contained a text file named -"<code>version</code>" whose first (and currently only) line is the version. -Older releases are <a href="https://ftp.iana.org/tz/releases/">archived</a>, -and are also available in an -<a href="ftp://ftp.iana.org/tz/releases/"><abbr -title="File Transfer Protocol">FTP</abbr> directory</a> via a -less secure protocol.</p> -<p>Alternatively, a development repository of code and data can be +“<code>version</code>” whose first (and currently only) line is the version. +<a href="https://ftp.iana.org/tz/releases/">Older archived releases are +available</a> via +<a href="https://en.wikipedia.org/wiki/HTTPS"><abbr +title="Hypertext Transfer Protocol Secure">HTTPS</abbr></a>, +<a href="https://en.wikipedia.org/wiki/Rsync"><abbr +title="remote sync">rsync</abbr></a>, and +<a href="https://en.wikipedia.org/wiki/FTP"><abbr +title="File Transfer Protocol">FTP</abbr></a>. +<p>Alternatively, a development repository of code and data can bem retrieved from <a href="https://github.com">GitHub</a> via the shell 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> @@ -194,7 +197,7 @@ After obtaining the code and data files, see the The code lets you compile the <code><abbr>tz</abbr></code> source files into machine-readable binary files, one for each location. The binary files are in a special format specified by -<a href="https://www.rfc-editor.org/rfc/9636">The +<a href="https://www.rfc-editor.org/rfc/rfc9636">The Time Zone Information Format (<abbr>TZif</abbr>)</a> (Internet <abbr title="Request For Comments">RFC</abbr> 9636). The code also lets @@ -208,9 +211,12 @@ location.</p> The <code><abbr>tz</abbr></code> code and data are by no means authoritative. If you find errors, please email changes to <a href="mailto:tz@iana.org"><code>tz@iana.org</code></a>, -the time zone mailing list. See +the time zone mailing list. +The mailing list and its archives are public, +so please do not send confidential information. +See <a href="https://lists.iana.org/postorius/lists/tz.iana.org/">the mailing -list's main page</a> to subscribe or to browse its archive of old messages. +list’s main page</a> to subscribe or to browse its archive of old messages. <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>. @@ -248,7 +254,7 @@ 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://gedit-technology.github.io/apps/gedit/">gedit</a>, and +<a href="https://gedit-text-editor.org">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 @@ -274,14 +280,15 @@ displays changes between recent <code><abbr>tzdb</abbr></code> versions. <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 +“<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, +daylight saving rules, please send email as described in +"<a href="#changes">Changes to the <code><abbr>tz</abbr></code> database</a>". +Do this 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 @@ -289,7 +296,7 @@ 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 +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. @@ -303,7 +310,7 @@ 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 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, @@ -313,9 +320,9 @@ 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 +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 Timing of Time Zone Changes</a>” for examples. </p> </section> @@ -331,7 +338,7 @@ database format.</li> <li><a href="https://blog.jonudell.net/2009/10/23/a-literary-appreciation-of-the-olsonzoneinfotz-database/">A literary appreciation of the Olson/Zoneinfo/tz database</a> comments on the -database's style.</li> +database’s style.</li> <li><a href="https://doi.org/10.1145/3340301.3341125">What time is it: managing time in the internet</a> analyzes the database longitudinally.</li> </ul> @@ -344,7 +351,7 @@ managing time in the internet</a> analyzes the database longitudinally.</li> These are listed roughly in ascending order of complexity and fanciness. </p> <ul> -<li><a href="https://time.is">Time.is</a> shows locations' +<li><a href="https://time.is">Time.is</a> shows locations’ time and zones.</li> <li><a href="https://www.timejones.com">TimeJones.com</a>, <a href="https://timezoneconverterapp.com">Time Zone Converter</a> and @@ -362,7 +369,7 @@ lets you see the <code><abbr>TZ</abbr></code> values directly.</li> <li><a href="https://www.convertit.com/Go/ConvertIt/World_Time/Current_Time.ASP">Current Time in 1000 Places</a> uses descriptions of the values.</li> -<li><a href="https://www.timeanddate.com/worldclock/">The World Clock – +<li><a href="https://www.timeanddate.com/worldclock/">The World Clock – Worldwide</a> lets you sort zone names and convert times.</li> <li><a href="https://24timezones.com">24TimeZones</a> has a world time map and a time converter.</li> @@ -376,21 +383,16 @@ calculates the current time difference between locations.</li> <section> <h2 id="protocols">Network protocols for <code><abbr>tz</abbr></code> data</h2> <ul> -<li>The <a href="https://www.ietf.org">Internet Engineering Task Force</a>'s -<a href="https://datatracker.ietf.org/wg/tzdist/charter/">Time Zone Data -Distribution Service (tzdist) working group</a> defined <a -href="https://www.rfc-editor.org/rfc/rfc7808">TZDIST</a> -(Internet <abbr>RFC</abbr> 7808), a time zone data distribution service, -along with <a href="https://www.rfc-editor.org/rfc/rfc7809">CalDAV</a> +<li><a href="https://www.rfc-editor.org/rfc/rfc7808">Time Zone +Data Distribution Service</a> (TZDIST, Internet <abbr>RFC</abbr> 7808) +is associated with +<a href="https://www.rfc-editor.org/rfc/rfc7809">CalDAV</a> (Internet <abbr>RFC</abbr> 7809), a calendar access protocol for transferring time zone data by reference. <a href="https://devguide.calconnect.org/Time-Zones/TZDS/">TZDIST -implementations</a> are available. -The <a href="https://www.ietf.org/mailman/listinfo/tzdist-bis">tzdist-bis -mailing list</a> discusses possible extensions.</li> -<li>The <a href="https://www.rfc-editor.org/rfc/rfc5545"> -Internet Calendaring and Scheduling Core Object Specification -(iCalendar)</a> (Internet <abbr>RFC</abbr> 5445) +implementations</a> are available.</li> +<li>The <a href="https://www.rfc-editor.org/rfc/rfc5545">iCalendar format</a> +(Internet <abbr>RFC</abbr> 5445) covers time zone data; see its VTIMEZONE calendar component. The iCalendar format requires specialized parsers and generators; a @@ -422,10 +424,6 @@ available under the <a href="https://www.gnu.org/copyleft/gpl.html"><abbr>GNU</abbr> General Public License (<abbr title="General Public License">GPL</abbr>)</a>.</li> -<li><a href="https://sourceforge.net/projects/tzical/">tziCal – tz -database conversion utility</a> is like Vzic, except for the <a -href="https://dotnet.microsoft.com">.NET framework</a> -and with a <abbr>BSD</abbr>-style license.</li> <li><a href="https://metacpan.org/release/DateTime-TimeZone">DateTime::TimeZone</a> contains a script <code>parse_olson</code> that compiles @@ -475,7 +473,7 @@ href="https://www.oracle.com/technetwork/articles/java/jf14-date-time-2125367.ht SE 8 Date and Time</a> <abbr>API</abbr> can be supplemented by <a href="https://www.threeten.org/threeten-extra/">ThreeTen-Extra</a>, which is freely available under a <abbr>BSD</abbr>-style license.</li> -<li><a href="https://www.joda.org/joda-time/">Joda-Time – Java date +<li><a href="https://www.joda.org/joda-time/">Joda-Time – Java date and time <abbr>API</abbr></a> contains a class <code>org.joda.time.tz.ZoneInfoCompiler</code> that compiles <code><abbr>tz</abbr></code> source into a binary format. It inspired @@ -484,7 +482,7 @@ they can assume Java 8 or later. It is available under the <a href="https://www.apache.org/licenses/LICENSE-2.0">Apache License</a>.</li> <li><a href="https://bell-sw.com/pages/iana-updater/">IANA Updater</a> and <a href="https://www.azul.com/products/open-source-tools/ziupdater-time-zone-tool/">ZIUpdater</a> -are alternatives to TZUpdater. IANA Updater's license is unclear; +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 @@ -499,7 +497,7 @@ License">LGPL</abbr>)</a>.</li> <li><abbr>ICU</abbr> (mentioned <a href="#ICU">above</a>) contains compilers and Java-based libraries.</li> </ul> -<li><a href="https://nodatime.org">Noda Time – Date and +<li><a href="https://nodatime.org">Noda Time – Date and time <abbr>API</abbr> for .NET</a> is like Joda-Time and Time4J, but for the .NET framework instead of Java. It is freely available under the Apache License.</li> @@ -548,13 +546,13 @@ The proposed <a href="https://github.com/tc39/proposal-temporal"><code>Temporal</code> 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 +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 compiler from <code><abbr>tz</abbr></code> source into <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> – +<li><a href="https://github.com/pavkam/tzdb"><abbr>TZDB</abbr> – <abbr>IANA</abbr> Time Zone Database for Delphi/<abbr title="Free Pascal Compiler">FPC</abbr></a> compiles from <code><abbr>tz</abbr></code> source into @@ -563,14 +561,14 @@ 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="https://pythonhosted.org/pytz/">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. In code that can assume Python 3.6 or later it is largely superseded; see <a href="https://blog.ganssle.io/articles/2018/03/pytz-fastest-footgun.html">pytz: The Fastest Footgun in the West</a>.</li> -<li><a href="https://tzinfo.github.io">TZInfo – +<li><a href="https://tzinfo.github.io">TZInfo – Ruby Timezone Library</a> compiles <code><abbr>tz</abbr></code> source into <a href="https://www.ruby-lang.org/en/">Ruby</a>. @@ -600,14 +598,14 @@ has an independent, thread-safe implementation of a <abbr>TZif</abbr> file reader. This library is freely available under the LGPL and is widely used in <abbr>GNU</abbr>/Linux systems.</li> -<li><a href="https://www.gnome.org">GNOME</a>'s +<li><a href="https://www.gnome.org">GNOME</a>’s <a href="https://developer.gnome.org/glib/">GLib</a> has a <abbr>TZif</abbr> file reader written in C that creates a <code>GTimeZone</code> object representing sets of <abbr>UT</abbr> offsets. It is freely available under the <abbr>LGPL</abbr>.</li> <li>The -<a href="https://github.com/bloomberg/bde/wiki">BDE Standard Library</a>'s +<a href="https://github.com/bloomberg/bde/wiki">BDE Standard Library</a>’s <code>baltzo::TimeZoneUtil</code> component contains a C++ implementation of a <abbr>TZif</abbr> file reader. It is freely available under the Apache License.</li> @@ -615,6 +613,9 @@ the Apache License.</li> library that translates between <abbr>UT</abbr> and civil time and can read <abbr>TZif</abbr> files. It is freely available under the Apache License.</li> +<li>The <a href="https://golang.org">Go programming language</a> +has a <abbr>TZif</abbr> file reader <a +href="https://pkg.go.dev/time#LoadLocationFromTZData"><code>LoadLocationFromTZData</code></a>.</li> <li>The <a href="https://github.com/nayarsystems/posix_tz_db"><code>posix_tz_db</code> package</a> contains Python code @@ -677,10 +678,6 @@ href="https://www.mozilla.org/en-US/thunderbird/">Thunderbird</a>. It displays multiple clocks in the application window, and has a mapping interface to <a href="https://www.google.com/earth/">Google Earth</a>. It is freely available under the <abbr>GPL</abbr>.</li> -<li><a href="https://golang.org">Go programming language</a> -implementations contain a copy of a 32-bit subset of a recent -<code><abbr>tz</abbr></code> database in a -Go-specific format.</li> <li>Microsoft Windows 8.1 and later has <code><abbr>tz</abbr></code> data and <abbr>CLDR</abbr> data (mentioned <a href="#CLDR">below</a>) used by the @@ -695,8 +692,8 @@ the older, proprietary method of Microsoft Windows 2000 and later, which stores time zone data in the <a href="https://en.wikipedia.org/wiki/Windows_Registry">Windows Registry</a>. The <a -href="https://unicode.org/cldr/charts/latest/supplemental/zone_tzid.html">Zone → -Tzid table</a> or <a +href="https://unicode.org/cldr/charts/latest/supplemental/zone_tzid.html">Zone +→ Tzid table</a> or <a href="https://github.com/unicode-org/cldr/blob/master/common/supplemental/windowsZones.xml"><abbr>XML</abbr> file</a> of the <abbr>CLDR</abbr> data maps proprietary zone IDs to <code><abbr>tz</abbr></code> names. @@ -714,7 +711,7 @@ Java-specific format.</li> <h2 id="other-dbs">Other time zone databases</h2> <ul> <li><a href="https://www.astro.com/atlas">Time-zone Atlas</a> -is Astrodienst's Web version of Shanks and Pottenger's out-of-print +is Astrodienst’s Web version of Shanks and Pottenger’s out-of-print time zone history atlases <a href="https://www.worldcat.org/oclc/468828649">for the US</a> and <a href="https://www.worldcat.org/oclc/76950459">for the world</a>. @@ -749,7 +746,7 @@ Agency (<abbr title="Central Intelligence Agency">CIA</abbr>)</a>, contains a time zone map; the <a -href="https://legacy.lib.utexas.edu/maps/world.html">Perry–Castañeda +href="https://legacy.lib.utexas.edu/maps/world.html">Perry–Castañeda Library Map Collection</a> of the University of Texas at Austin has copies of recent editions. @@ -759,14 +756,13 @@ and parts of the data are a few years out of date.</li> <li><a href="https://www.worldtimezone.com">World Time Zone Map with current time</a> has several fancy time zone maps; it covers Russia particularly well. -The maps' pictorial quality is not quite as good as the -<abbr>CIA</abbr>'s +The maps’ pictorial quality is not quite as good as the <abbr>CIA</abbr>’s but the maps are more up to date.</li> <li><a href="https://blog.poormansmath.net/how-much-is-time-wrong-around-the-world/">How much is time wrong around the world?</a> maps the difference between mean solar and standard time, highlighting areas such as western China -where the two differ greatly. It's a bit out of date, unfortunately.</li> +where the two differ greatly. It’s a bit out of date, unfortunately.</li> </ul> </section> @@ -799,25 +795,25 @@ Commercial network API access is provided by <a href="https://askgeo.com">AskGeo</a> and <a href="https://www.geogarage.com/blog/news-1/post/geogarage-time-zone-api-31">GeoGarage</a>. </li> -<li>"<a +<li>“<a href="https://stackoverflow.com/questions/16086962/how-to-get-a-time-zone-from-a-location-using-latitude-and-longitude-coordinates/16086964">How to get a time zone from a location using latitude and longitude -coordinates?</a>" discusses other geolocation possibilities.</li> +coordinates?</a>” discusses other geolocation possibilities.</li> <li><a href="http://statoids.com/statoids.html">Administrative -Divisions of Countries ("Statoids")</a> lists +Divisions of Countries (“Statoids”)</a> lists political subdivision data related to time zones.</li> <li><a href="https://manifold.net/info/freestuff.shtml">Manifold Software -– GIS and Database Tools</a> includes a Manifold-format map of +– GIS and Database Tools</a> includes a Manifold-format map of world time zone boundaries circa 2007, distributed under the <abbr>GPL</abbr>.</li> <li>A ship within the <a href="https://en.wikipedia.org/wiki/Territorial_waters">territorial -waters</a> of any nation uses that nation's time. In international -waters, time zone boundaries are meridians 15° apart, except that -<abbr>UT</abbr>−12 and <abbr>UT</abbr>+12 are each 7.5° +waters</a> of any nation uses that nation’s time. In international +waters, time zone boundaries are meridians 15° apart, except that +<abbr>UT</abbr>−12 and <abbr>UT</abbr>+12 are each 7.5° wide and are separated by -the 180° meridian (not by the International Date Line, which is -for land and territorial waters only). A captain can change ship's +the 180° meridian (not by the International Date Line, which is +for land and territorial waters only). A captain can change ship’s clocks any time after entering a new time zone; midnight changes are common.</li> </ul> @@ -831,12 +827,13 @@ Walk through Time</a> surveys the evolution of timekeeping.</li> <li>The history of daylight saving time is surveyed in <a href="http://www.webexhibits.org/daylightsaving/">About Daylight -Saving Time – History, rationale, laws & dates</a> and summarized in +Saving Time – History, rationale, laws & dates</a> and summarized in <a href="http://seizethedaylight.com/dst/">A Brief History of Daylight Saving Time</a>.</li> <li><a href="https://www.laphamsquarterly.org/roundtable/time-lords">Time Lords</a> discusses how authoritarians manipulate civil time.</li> -<li><a href="https://www.w3.org/TR/timezone/">Working with Time Zones</a> +<li><a href="https://www.w3.org/TR/timezone/">Working with Time +and Time Zones</a> contains guidelines and best practices for software applications that deal with civil time.</li> <li><a href="https://webspace.science.uu.nl/~gent0113/idl/idl.htm">A History of @@ -851,10 +848,7 @@ Zone Concepts</a> discusses terminological issues behind time zones.</li> <h2 id="national">National histories of legal time</h2> <dl> <dt>Australia</dt> -<dd>The Parliamentary Library commissioned a <a -href="https://parlinfo.aph.gov.au/parlInfo/download/library/prspub/359V6/upload_binary/359v60.pdf">research -paper on daylight saving time in Australia</a>. -The Bureau of Meteorology publishes a list of <a +<dd>The Bureau of Meteorology publishes a list of <a href="http://www.bom.gov.au/climate/averages/tables/dst_times.shtml">Implementation Dates of Daylight Savings Time within Australia</a>.</dd> <dt>Belgium</dt> @@ -867,7 +861,7 @@ hreflang="fr">French</a>).</dd> <dt>Brazil</dt> <dd>The Time Service Department of the National Observatory records <a href="http://pcdsh01.on.br/DecHV.html" -hreflang="pt-BR">Brazil's daylight saving time decrees (in +hreflang="pt-BR">Brazil’s daylight saving time decrees (in Portuguese)</a>.</dd> <dt>Canada</dt> <dd>National Research Council Canada publishes current @@ -877,12 +871,12 @@ zones and daylight saving time</a>.</dd> <dt>Chile</dt> <dd>The Hydrographic and Oceanographic Service of the Chilean Navy publishes a <a href="https://www.horaoficial.cl/historia_hora.php" hreflang="es">history of -Chile's official time (in Spanish)</a>.</dd> +Chile’s official time (in Spanish)</a>.</dd> <dt>China</dt> <dd>The Hong Kong Observatory maintains a <a href="https://www.hko.gov.hk/en/gts/time/Summertime.htm">history of summer time in Hong Kong</a>, -and Macau's Meteorological and Geophysical Bureau maintains a <a +and Macau’s Meteorological and Geophysical Bureau maintains a <a href="https://www.smg.gov.mo/en/subpage/224/page/174">similar history for Macau</a>. Unfortunately the latter is incomplete and has errors.</dd> @@ -915,8 +909,8 @@ covers the history of local time in the Netherlands from ancient times.</dd> href="https://www.dia.govt.nz/Daylight-Saving-History">History of Daylight Saving</a>.</dd> <dt>Palestine</dt> -<dd>The Ministry of Telecom and IT publishes a <a -href="https://mtit.pna.ps/home/TimeZone" +<dd>The Ministry of Telecom and Digital Economy publishes a <a +href="https://mtde.gov.ps/home/TimeZone" hreflang="ar">history of clock changes (in Arabic)</a>.</dd> <dt>Portugal</dt> <dd>The Lisbon Astronomical Observatory publishes a @@ -925,7 +919,7 @@ legal time (in Portuguese)</a>.</dd> <dt>Singapore</dt> <dd><a id="Singapore" 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 history of legal time in Singapore and Malaysia.</dd> <dt>United Kingdom</dt> <dd><a @@ -933,7 +927,7 @@ href="https://www.polyomino.org.uk/british-time/">History of legal time in Britain</a> discusses in detail the country with perhaps the best-documented history of clock adjustments.</dd> <dt>United States</dt> -<dd>The Department of Transportation's <a +<dd>The Department of Transportation’s <a href="https://www.transportation.gov/regulations/recent-time-zone-proceedings">Recent Time Zone Proceedings</a> lists changes to official written time zone boundaries, and its <a @@ -957,9 +951,6 @@ zone shifts, and many scientific studies have been conducted. This section summarizes reviews and position statements based on scientific literature in the area.</p> <ul> -<li>In 2022 the American Medical Association issued a -<a href="https://www.ama-assn.org/press-center/press-releases/ama-calls-permanent-standard-time">statement -supporting permanent standard time</a> on health grounds.</li> <li>Carey RN, Sarma KM. <a href="https://bmjopen.bmj.com/content/7/6/e014319.long">Impact of daylight saving time on road traffic collision risk: a systematic @@ -969,13 +960,35 @@ This reviews research literature and concludes that the evidence neither supports nor refutes road safety benefits from shifts in time zones.</li> <li>Havranek T, Herman D, Irsova D. -<a href="https://www.iaee.org/en/publications/ejarticle.aspx?id=3051">Does -daylight saving save electricity? A meta-analysis</a>. -<em>Energy J.</em> 2018;39(2):35–61. +Does daylight saving save electricity? A meta-analysis. +<em>Energy J.</em> 2018;39(2):35–61. doi:<a href="https://doi.org/10.5547/01956574.39.2.thav">10.5547/01956574.39.2.thav</a>. -This analyzes research literature and concludes, "Electricity savings +This analyzes research literature and concludes, “Electricity savings are larger for countries farther away from the equator, while -subtropical regions consume more electricity because of <abbr>DST</abbr>."</li> +subtropical regions consume more electricity because of <abbr>DST</abbr>.”</li> +<li>Neumann P, von Blanckenburg K. <a +href="https://journals.sagepub.com/doi/full/10.1177/0961463X241310562">What +time will it be? A comprehensive literature review on daylight saving time</a>. +<em>Time Soc</em>. 2025-01-21. +doi:<a href="https://doi.org/10.1177/0961463X241310562">10.1177/0961463X241310562</a>. +This reviews DST’s effects on electricity, health, crime, road safety, +and the economy, focusing on research since 2010, and concludes that +year-round standard time is preferable overall. +</ul> + +<p>The following medical societies have taken positions on the +advisability of clock shifts:</p> + +<ul> +<li>In 2022 the American Medical Association issued a +<a href="https://www.ama-assn.org/press-center/press-releases/ama-calls-permanent-standard-time">statement +supporting permanent standard time</a> on health grounds.</li> +<li>Crawford MR, Winnebeck EC, von Schantz M <em>et al</em>. +<a href="https://onlinelibrary.wiley.com/doi/10.1111/jsr.14352">The +British Sleep Society position statement on Daylight Saving Time in the UK</a>. +<em>J Sleep Res.</em> 2025;34(3):e14352. +doi:<a href="https://doi.org/10.1111/jsr.14352">10.1111/jsr.14352</a>. +This recommends that the UK abolish DST for health reasons.</li> <li>Malow BA. <a href="https://academic.oup.com/sleep/article/45/12/zsac236/6717940">It is time to abolish the clock change and adopt permanent @@ -984,20 +997,12 @@ a Sleep Research Society position statement</a>. <em>Sleep.</em> 2022;45(12):zsac236. doi:<a href="https://doi.org/10.1093/sleep/zsac236">10.1093/sleep/zsac236</a>. After reviewing the scientific literature, the Sleep Research Society -advocates permanent standard time due to its health benefits. -<li>Neumann P, von Blanckenburg K. <a -href="https://journals.sagepub.com/doi/full/10.1177/0961463X241310562">What -time will it be? A comprehensive literature review on daylight saving time</a>. -<em>Time Soc</em>. 2025-01-21. -doi:<a href="https://doi.org/10.1177/0961463X241310562">10.1177/0961463X241310562</a>. -This reviews DST's effects on electricity, health, crime, road safety, -and the economy, focusing on research since 2010, and concludes that -year-round standard time is preferable overall. +advocates permanent standard time due to its health benefits.</li> <li>Rishi MA, Cheng JY, Strang AR <em>et al</em>. <a href="https://jcsm.aasm.org/doi/10.5664/jcsm.10898">Permanent standard time is the optimal choice for health and safety: an American Academy of Sleep Medicine position statement</a>. -<em>J Clin Sleep Med.</em> 2024;20(1):121–125. +<em>J Clin Sleep Med.</em> 2024;20(1):121–125. doi:<a href="https://doi.org/10.5664/jcsm.10898">10.5664/jcsm.10898</a>. The AASM argues for permanent standard time due to health and safety risks and economic costs of both <abbr>DST</abbr> transitions and @@ -1005,12 +1010,12 @@ permanent <abbr>DST</abbr>.</li> <li>Roenneberg T, Wirz-Justice A, Skene DJ <em>et al</em>. <a href="https://journals.sagepub.com/doi/10.1177/0748730419854197">Why should we abolish Daylight Saving Time?</a> -<em>J Biol Rhythms.</em> 2019;34(3):227–230. +<em>J Biol Rhythms.</em> 2019;34(3):227–230. doi:<a href="https://doi.org/10.1177/0748730419854197">10.1177/0748730419854197</a>. The Society for Research on Biological Rhythms opposes <abbr>DST</abbr> changes and permanent <abbr>DST</abbr>, and advocates that governments adopt -"permanent Standard Time for the health and safety of their citizens".</li> +“permanent Standard Time for the health and safety of their citizens”.</li> </ul> </section> @@ -1044,14 +1049,14 @@ Options for <abbr title="Dynamic Host Configuration Protocol">DHCP</abbr></a> specifies a <a href="https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol"><abbr>DHCP</abbr></a> option for a server to configure -a client's time zone and daylight saving settings automatically.</li> +a client’s time zone and daylight saving settings automatically.</li> <li><a href="https://www.ucolick.org/~sla/leapsecs/timescales.html">Time Scales</a> describes astronomical time scales like <abbr title="Terrestrial Dynamic Time">TDT</abbr>, <abbr title="Geocentric Coordinate Time">TCG</abbr>, and <abbr title="Barycentric Dynamic Time">TDB</abbr>. <li>The <a href="https://www.iau.org"><abbr -title="International Astronomical Union">IAU</abbr></a>'s <a +title="International Astronomical Union">IAU</abbr></a>’s <a href="https://www.iausofa.org"><abbr title="Standards Of Fundamental Astronomy">SOFA</abbr></a> collection contains C and <a @@ -1063,7 +1068,7 @@ code for converting among time scales like <a href="https://www.iausofa.org/tandc.html">SOFA license</a>.</li> <li><a href="https://www.giss.nasa.gov/tools/mars24/help/notes.html">Mars24 Sunclock -– Time on Mars</a> describes Airy Mean Time (<abbr>AMT</abbr>) and the +– Time on Mars</a> describes Airy Mean Time (<abbr>AMT</abbr>) and the diverse local time scales used by each landed mission on Mars.</li> <li><a href="http://leapsecond.com">LeapSecond.com</a> is @@ -1072,25 +1077,26 @@ in general. It covers the state of the art in amateur timekeeping, and how the art has progressed over the past few decades.</li> <li>The rules for leap seconds are specified in Annex 1 (Time scales) of <a href="https://www.itu.int/rec/R-REC-TF.460-6-200202-I/">Standard-frequency -and time-signal emissions</a>, International Telecommunication Union – +and time-signal emissions</a>, International Telecommunication Union – Radiocommunication Sector (ITU-R) Recommendation TF.460-6 (02/2002).</li> <li><a href="https://www.iers.org/IERS/EN/Publications/Bulletins/bulletins.html"><abbr title="International Earth Rotation and Reference Systems Service">IERS</abbr> Bulletins</a> contains official publications of the International Earth Rotation and Reference Systems Service, which decides when leap -seconds occur. The <code><abbr>tz</abbr></code> code and data support leap seconds -via an optional "<code>right</code>" configuration where a computer's internal +seconds occur. +The <code><abbr>tz</abbr></code> code and data support leap seconds +via an optional <code>"right"</code> configuration where a computer’s internal <code>time_t</code> integer clock counts every <abbr>TAI</abbr> second, -as opposed to the default "<code>posix</code>" configuration +as opposed to the default <code>"posix"</code> configuration where the internal clock ignores leap seconds. The two configurations agree for timestamps starting with 1972-01-01 00:00:00 <abbr>UTC</abbr> (<code>time_t</code> 63 072 000) and diverge for timestamps starting with <code>time_t</code> 78 796 800, 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 -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 1972 even though the historical situation is messy, partly because neither <abbr>UTC</abbr> nor <abbr>TAI</abbr> @@ -1105,7 +1111,7 @@ The <abbr>IERS</abbr> maintains this file, and a copy is distributed by 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 +as well as in the <code>"right"</code> configuration in binary form; for example, <code>right/UTC</code> can be used by <a href="https://chrony-project.org"><code>chrony</code></a>, another <abbr>NTP</abbr> implementation.</li> @@ -1114,13 +1120,13 @@ 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 half second, even though every <abbr>POSIX</abbr> minute has exactly 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 the abovementioned <abbr>NTP</abbr> implementations, <a href="https://github.com/google/unsmear">supports</a> conversion between <abbr>UTC</abbr> and smeared <abbr>POSIX</abbr> timestamps, and is used by major cloud service providers. However, according to -<a href="https://www.rfc-editor.org/rfc/rfc8633#section-3.7.1">§3.7.1 of +<a href="https://www.rfc-editor.org/rfc/rfc8633#section-3.7.1">§3.7.1 of Network Time Protocol Best Current Practices</a> (Internet <abbr>RFC</abbr> 8633), leap smearing is not suitable for applications requiring accurate <abbr>UTC</abbr> or civil time, @@ -1129,7 +1135,7 @@ and is intended for use only in single, well-controlled environments.</li> href="https://pairlist6.pair.net/mailman/listinfo/leapsecs">Leap Second Discussion List</a> covers <a 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 <a href="https://www.cl.cam.ac.uk/~mgk25/time/metrologia-leapsecond.pdf">The leap second: its history and possible future</a>. @@ -1143,12 +1149,16 @@ to discontinue the use of leap seconds by 2035, and requested that no 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. -<a href="https://www.preprints.org/manuscript/202406.0043/v1">A proposal -to change the leap-second adjustments to Coordinated Universal Time</a> -(doi:<a href="https://doi.org/10.1088/1681-7575/ad6266">10.1088/1681-7575/ad6266</a>) -would replace leap seconds with 13-second leap smears occurring once per +in 2023</a> to cooperate with this process. One proposal to implement this +would replace leap seconds with seven 13-second leap smears occurring once per decade until 2100, with leap smears after that gradually increasing in size. +See: +<ul> +<li>Levine J. <a href="https://www.preprints.org/manuscript/202406.0043/v1">A +proposal to change the leap-second adjustments to +coordinated universal time</a>. <em>Metrologia.</em> 2024;61(5):055002. doi:<a +href="https://doi.org/10.1088/1681-7575/ad6266">10.1088/1681-7575/ad6266</a>.</li> +</ul> However, there is still no consensus on whether this is the best way to replace leap seconds. </li> @@ -1161,9 +1171,8 @@ to replace leap seconds. <li>The <a id="CLDR" href="https://cldr.unicode.org">Unicode Common Locale Data Repository (<abbr>CLDR</abbr>) Project</a> has localizations for time zone names, abbreviations, identifiers, and formats. For example, it -contains French translations for "Eastern European Summer Time", -"<abbr title="Eastern European Summer Time">EEST</abbr>", and -"Bucharest". Its +contains French translations for “Eastern European Summer Time”, +“<abbr title="Eastern European Summer Time">EEST</abbr>”, and “Bucharest”. Its <a href="https://unicode.org/cldr/charts/latest/by_type/">by-type charts</a> show these values for many locales. Data values are available in both <abbr title="Locale Data Markup Language">LDML</abbr> @@ -1174,13 +1183,13 @@ the international standard date and time notation</a> covers <a href="https://www.iso.org/standard/70907.html"><em><abbr title="International Organization for Standardization">ISO</abbr> -8601-1:2019 – Date and time – Representations for information -interchange – Part 1: Basic rules</em></a>.</li> +8601-1:2019 – Date and time – Representations for information +interchange – Part 1: Basic rules</em></a>.</li> <li> <a href="https://www.w3.org/TR/xmlschema/#dateTime"><abbr>XML</abbr> -Schema: Datatypes – dateTime</a> specifies a format inspired by +Schema: Datatypes – dateTime</a> specifies a format inspired by <abbr>ISO</abbr> 8601 that is in common use in <abbr>XML</abbr> data.</li> -<li><a href="https://www.rfc-editor.org/rfc/rfc5322#section-3.3">§3.3 of +<li><a href="https://www.rfc-editor.org/rfc/rfc5322#section-3.3">§3.3 of Internet Message Format</a> (Internet <abbr>RFC</abbr> 5322) specifies the time notation used in email and <a href="https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol"><abbr>HTTP</abbr></a> @@ -1193,7 +1202,7 @@ An extension, <a href="https://www.rfc-editor.org/rfc/rfc9557">Date and Time on the Internet: Timestamps with Additional Information</a> (Internet <abbr>RFC</abbr> 9557) extends this profile to let you specify the <code><abbr>tzdb</abbr></code> timezone of a timestamp -via suffixes like "<code>[Asia/Tokyo]</code>". +via suffixes like <code>[Asia/Tokyo]</code>. <li> <a href="https://web.archive.org/web/20190130042457/https://www.hackcraft.net/web/datetime/">Date & Time Formats on the Web</a> surveys web- and Internet-oriented date and time @@ -1201,17 +1210,17 @@ formats.</li> <li>Alphabetic time zone abbreviations should not be used as unique identifiers for <abbr>UT</abbr> offsets as they are ambiguous in practice. For example, in English-speaking North America -"<abbr>CST</abbr>" denotes 6 hours behind <abbr>UT</abbr>, +“<abbr>CST</abbr>” denotes 6 hours behind <abbr>UT</abbr>, but in China it denotes 8 hours ahead of <abbr>UT</abbr>, and French-speaking North Americans prefer -"<abbr title="Heure Normale du Centre">HNC</abbr>" to -"<abbr>CST</abbr>". The <code><abbr>tz</abbr></code> +“<abbr title="Heure Normale du Centre">HNC</abbr>” to +“<abbr>CST</abbr>”. The <code><abbr>tz</abbr></code> database contains English abbreviations for many timestamps; -unfortunately some of these abbreviations were merely the database maintainers' +unfortunately some of these abbreviations were merely the database maintainers’ inventions, and these have been removed when possible.</li> <li>Numeric time zone abbreviations typically count hours east of <abbr>UT</abbr>, e.g., +09 for Japan and -−10 for Hawaii. However, <abbr>POSIX</abbr> proleptic +−10 for Hawaii. However, <abbr>POSIX</abbr> proleptic <code><abbr>TZ</abbr></code> settings use the opposite convention. For example, one might use <code><abbr>TZ</abbr>="<abbr title="Japan Standard Time">JST</abbr>-9"</code> and @@ -1225,7 +1234,7 @@ any future changes to the rules. One should never set <abbr>POSIX</abbr> <code><abbr>TZ</abbr></code> to a value like <code>"GMT-9"</code>, though, since this would incorrectly imply that local time is nine hours ahead of <abbr>UT</abbr> and the time zone -is called "<abbr>GMT</abbr>".</li> +is called “<abbr>GMT</abbr>”.</li> </ul> </section> @@ -1245,6 +1254,8 @@ This web page is in the public domain, so clarified as of <br> Please send corrections to this web page to the <a href="mailto:tz@iana.org">time zone mailing list</a>. +The mailing list and its archives are public, +so please do not send confidential information. </footer> </body> </html> |