- tz - lists.iana.org

wrong Europe/Dublin dst offset rule
by Vicky May 30, 2018

May 30, 2018

Hi, while parsing the data i found the issue in rule Europe/Dublin Negative DST.. Previous version or not in any other file there is no negative dst. DST either start and end . # The following is like GB-Eire and EU, except with standard time in # summer and negative daylight saving time in winter. # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S Rule Eire 1971 only - Oct 31 2:00u -1:00 GMT Rule Eire 1972 1980 - Mar Sun>=16 2:00u 0 IST Rule Eire 1972 1980 - Oct Sun>=23 2:00u -1:00 GMT Rule Eire 1981 max - Mar lastSun 1:00u 0 IST Rule Eire 1981 1989 - Oct Sun>=23 1:00u -1:00 GMT Rule Eire 1990 1995 - Oct Sun>=22 1:00u -1:00 GMT Rule Eire 1996 max - Oct lastSun 1:00u -1:00 GMT Please explain why -ve dst offset compared with other files. Regards, Vaibhav

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[PROPOSED 1/3] * tz-link.html: Macao → Macau
by Paul Eggert May 28, 2018

May 28, 2018

--- tz-link.html | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tz-link.html b/tz-link.html index 508a1f1..d307bf7 100644 --- a/tz-link.html +++ b/tz-link.html @@ -754,8 +754,8 @@ hreflang="he">announcements (in Hebrew)</a>.</dd> <dd>The National Institute of Metrological Research maintains a <a href="http://www.nanospin.eu/res/tf/ora_legale_i.shtml">table of civil time (in Italian)</a>.</dd> -<dt>Macao</dt> -<dd>The Macao Meteorological and Geophysical Bureau maintains a +<dt>Macau</dt> +<dd>The Meteorological and Geophysical Bureau maintains a <a href="http://www.smg.gov.mo/smg/geophysics/e_t_Summer%20Time.htm">history of summer time</a>. Unfortunately it is incomplete and has errors.</dd> <dt>Malaysia</dt> -- 2.17.0

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Asia\Nicosia
by GsaTitanium May 26, 2018

May 26, 2018

Hello, i am writing to you about an issue with Nicosia the capital of Cyprus. Cyprus is an EU member since May 1st 2004 which makes it a European country but you have it as an Asia Continent Country. Before May 1st 2004 Cyprus had Asia Timezone but since then we have Eastern European Time and we have also adopted the Eastern European Summer Time. Basically you representation of Nicosia as UTC+2 and UTC+3 (in summer) time is correct but in the wrong Continent. Cyprus as a European Union Member: https://europa.eu/european-union/about-eu/countries/member-countries/cyprus… Map of Europe Union including Cyprus: https://europa.eu/european-union/about-eu/countries_en?country=CY#map Waiting for you reply Thank you GsaTitanium

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[PROPOSED 1/2] * tz-link.html: Update tzdist URLs.
by Paul Eggert May 25, 2018

May 25, 2018

--- tz-link.html | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tz-link.html b/tz-link.html index 3017a5e..508a1f1 100644 --- a/tz-link.html +++ b/tz-link.html @@ -281,11 +281,11 @@ transferring time zone data by reference. The <a href="https://www.ietf.org/mailman/listinfo/tzdist-bis">tzdist-bis mailing list</a> discusses two Internet drafts: <a id="TZDIST-Geolocate" -href="https://tools.ietf.org/html/draft-murchison-tzdist-geolocate-01">TZDIST +href="https://tools.ietf.org/html/draft-murchison-tzdist-geolocate-02">TZDIST Geolocate Extension</a> lets a client determine its time zone region from its geographic location using a <a href="https://tools.ietf.org/html/rfc5870">'geo' URI</a>, and -<a href="https://tools.ietf.org/html/draft-murchison-tzdist-tzif-00">The +<a href="https://tools.ietf.org/html/draft-murchison-tzdist-tzif-02">The Time Zone Information Format (<abbr>TZif</abbr>)</a> specifies the format of <abbr>TZif</abbr> data.</li> <li>The <a href="https://tools.ietf.org/html/rfc5545"> -- 2.17.0

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Thanks for the book recommendation
by Scott Kilpatrick May 25, 2018

May 25, 2018

Hi everyone, Recently I stumbled upon the tz database and mailing list when debugging some daylight saving issues at work. I'd just wanted to understand how political decisions about DST affect a Java program. Reading through the documentation about the database online, I noticed the link to the Dissent interview with Vanessa Ogle about her book, "The Global Transformation of Time, 1870-1950". (It was a bit jarring to see a link to Dissent in technical material like this, ha!) First I read that interview and then I picked up the book - and loved it! Many thanks to Paul E. or to whomever actually suggested the citation to the book in the "theory" page. It has helped me further go down this rabbit hole that I'd never expected to be so interested in. Best, Scott

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[PATCH] Clarify that EST5EDT is problematic in POSIX
by Paul Eggert May 21, 2018

May 21, 2018

* theory.html: Don’t imply that EST5EDT is an OK POSIX TZ string, as POSIX does not specify the DST transitions in this case. Use past tense to describe the typical pre-POSIX behavior. Minor copyediting. --- theory.html | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/theory.html b/theory.html index 53f7cee..298972e 100644 --- a/theory.html +++ b/theory.html @@ -874,15 +874,15 @@ an older <code>zic</code>. <pre><code>TZ='Pacific/Auckland'</code></pre> </li> <li> - POSIX does not define the exact meaning of <code>TZ</code> values like + POSIX does not define the <abbr>DST</abbr> transitions + for <code>TZ</code> values like "<code>EST5EDT</code>". - Typically the current <abbr>US</abbr> <abbr>DST</abbr> rules - are used to interpret such values, but this means that the - <abbr>US</abbr> <abbr>DST</abbr> rules are compiled into each - program that does time conversion. - This means that when - <abbr>US</abbr> time conversion rules change (as in the United - States in 1987), all programs that do time conversion must be + Traditionally the current <abbr>US</abbr> <abbr>DST</abbr> rules + were used to interpret such values, but this meant that the + <abbr>US</abbr> <abbr>DST</abbr> rules were compiled into each + program that did time conversion. This meant that when + <abbr>US</abbr> time conversion rules changed (as in the United + States in 1987), all programs that did time conversion had to be recompiled to ensure proper results. </li> <li> @@ -893,14 +893,14 @@ an older <code>zic</code>. <li> In POSIX, there is no tamper-proof way for a process to learn the system's best idea of local wall clock. - (This is important for applications that an administrator wants + This is important for applications that an administrator wants used only at certain times – without regard to whether the user has fiddled the <code>TZ</code> environment variable. While an administrator can "do everything in <abbr>UT</abbr>" to get around the problem, doing so is inconvenient and precludes - handling daylight saving time shifts - as might be required to - limit phone calls to off-peak hours.) + handling daylight saving time shifts – as might be required to + limit phone calls to off-peak hours. </li> <li> POSIX provides no convenient and efficient way to determine @@ -923,7 +923,7 @@ an older <code>zic</code>. Unsigned 32-bit integers are used on one or two platforms, and 36-bit and 40-bit integers are also used occasionally. Although earlier POSIX versions allowed <code>time_t</code> to be a - floating-point type, this was not supported by any practical systems, + floating-point type, this was not supported by any practical system, and POSIX.1-2013 and the <code><abbr>tz</abbr></code> code both require <code>time_t</code> to be an integer type. </li> @@ -960,9 +960,9 @@ an older <code>zic</code>. separately maintaining both <code>TZ</code> and <code>TIMEZONE</code> seemed a nuisance; and systems where "new" forms of <code>TZ</code> might cause problems can simply - use <code>TZ</code> values such as "<code>EST5EDT</code>" which - can be used both by "new" programs (à la POSIX) and "old" - programs (as zone names and offsets). + use legacy <code>TZ</code> values such as "<code>EST5EDT</code>" which + can be used by "new" programs as well as by "old" programs that + assume pre-POSIX <code>TZ</code> values. </p> </li> <li> -- 2.17.0

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[PROPOSED] Use “TZif” for binary files.
by Paul Eggert May 21, 2018

May 21, 2018

Also, mention tzdist-bis and draft-murchison-tzdist-tzif-00. --- Makefile | 8 +++++--- NEWS | 2 ++ theory.html | 15 ++++++++------- tz-link.html | 37 ++++++++++++++++++++++--------------- zic.c | 2 +- 5 files changed, 38 insertions(+), 26 deletions(-) diff --git a/Makefile b/Makefile index 91c30f7..06f7fd6 100644 --- a/Makefile +++ b/Makefile @@ -109,6 +109,8 @@ LIBDIR = $(TOPDIR)/$(USRDIR)/lib # Types to try, as an alternative to time_t. int64_t should be first. TIME_T_ALTERNATIVES = int64_t int32_t uint32_t uint64_t +# What kind of TZif data files to generate. +# (TZif is the binary time zone data format that zic generates.) # If you want only POSIX time, with time values interpreted as # seconds since the epoch (not counting leap seconds), use # REDO= posix_only @@ -129,7 +131,7 @@ TIME_T_ALTERNATIVES = int64_t int32_t uint32_t uint64_t REDO= posix_right -# To install data in text form that has all the information of the binary data, +# To install data in text form that has all the information of the TZif data, # (optionally incorporating leap second information), use # TZDATA_TEXT= tzdata.zi leapseconds # To install text data without leap second information (e.g., because @@ -357,7 +359,7 @@ ZIC= $(zic) $(ZFLAGS) ZFLAGS= -# How to use zic to install tz binary files. +# How to use zic to install TZif files. ZIC_INSTALL= $(ZIC) -d '$(DESTDIR)$(TZDIR)' $(LEAPSECONDS) @@ -605,7 +607,7 @@ INSTALLARGS = \ YEARISTYPE='$(YEARISTYPE)' \ ZIC='$(ZIC)' -# 'make install_data' installs one set of tz binary files. +# 'make install_data' installs one set of TZif files. install_data: zic leapseconds yearistype tzdata.zi $(ZIC_INSTALL) tzdata.zi diff --git a/NEWS b/NEWS index a91f00a..6bd89c2 100644 --- a/NEWS +++ b/NEWS @@ -25,6 +25,8 @@ Unreleased, experimental changes The latter restriction makes room for future extensions (a possibility noted by Tom Lane). + The name "TZif" is now used for the tz binary data format. + Changes to build procedure New 'make' target 'rearguard_tarballs' to build the rearguard diff --git a/theory.html b/theory.html index d5055b2..f2409f4 100644 --- a/theory.html +++ b/theory.html @@ -932,15 +932,16 @@ an older <code>zic</code>. <li> <p> The <code>TZ</code> environment variable is used in generating - the name of a binary file from which time-related information is read + the name of a file from which time-related information is read (or is interpreted à la POSIX); <code>TZ</code> is no longer - constrained to be a three-letter time zone - abbreviation followed by a number of hours and an optional three-letter - daylight time zone abbreviation. + constrained to be a string containing abbreviations + and numeric data as described <a href="#POSIX">above</a>. + The file's format is <dfn><abbr>TZif</abbr></dfn>, + a time zone information format that contains binary data. The daylight saving time rules to be used for a particular <code><abbr>tz</abbr></code> region are encoded in the - binary file; the format of the file - allows U.S., Australian, and other rules to be encoded, and + <abbr>TZif</abbr> file; the format of the file allows <abbr>US</abbr>, + Australian, and other rules to be encoded, and allows for situations where more than two time zone abbreviations are used. </p> @@ -950,7 +951,7 @@ an older <code>zic</code>. might cause "old" programs (that expect <code>TZ</code> to have a certain form) to operate incorrectly; consideration was given to using some other environment variable (for example, <code>TIMEZONE</code>) - to hold the string used to generate the binary file's name. + to hold the string used to generate the <abbr>TZif</abbr> file's name. In the end, however, it was decided to continue using <code>TZ</code>: it is widely used for time zone purposes; separately maintaining both <code>TZ</code> diff --git a/tz-link.html b/tz-link.html index b8b7944..77e06d2 100644 --- a/tz-link.html +++ b/tz-link.html @@ -143,8 +143,10 @@ more errors.</p> After obtaining the code and data files, see the <code>README</code> file for what to do next. The code lets you compile the <code><abbr>tz</abbr></code> source files into -machine-readable binary files, one for each location. It also lets -you read a <code><abbr>tz</abbr></code> binary file and interpret time stamps for that +machine-readable binary files, one for each location. The binary files +are in a special time zone information format (<dfn><abbr>TZif</abbr></dfn>). +The code also lets +you read a <abbr>TZif</abbr> file and interpret time stamps for that location.</p> <h2 id="changes">Changes to the <code><abbr>tz</abbr></code> database</h2> <p> @@ -272,12 +274,17 @@ href="https://tools.ietf.org/html/rfc7808">TZDIST</a> (Internet <abbr>RFC</abbr> 7808), a time zone data distribution service, along with <a href="https://tools.ietf.org/html/rfc7809">CalDAV</a> (Internet <abbr>RFC</abbr> 7809), a calendar access protocol for -transferring time zone data by reference. The draft <a +transferring time zone data by reference. +The <a href="https://www.ietf.org/mailman/listinfo/tzdist-bis">tzdist-bis +mailing list</a> discusses two Internet drafts: <a id="TZDIST-Geolocate" href="https://tools.ietf.org/html/draft-murchison-tzdist-geolocate-01">TZDIST Geolocate Extension</a> lets a client determine its time zone region from its geographic location using a <a -href="https://tools.ietf.org/html/rfc5870">'geo' URI</a>.</li> +href="https://tools.ietf.org/html/rfc5870">'geo' URI</a>, and +<a href="https://tools.ietf.org/html/draft-murchison-tzdist-tzif-00">The +Time Zone Information Format (<abbr>TZif</abbr>)</a> specifies the format of +<abbr>TZif</abbr> data.</li> <li>The <a href="https://tools.ietf.org/html/rfc5545"> Internet Calendaring and Scheduling Core Object Specification (iCalendar)</a> (Internet <abbr>RFC</abbr> 5445) @@ -426,35 +433,35 @@ source into text files, along with a runtime that can read those files. Tcl is freely available under a <abbr>BSD</abbr>-style license.</li> </ul> -<h2 id="binary">Other <code><abbr>tz</abbr></code> binary file readers</h2> +<h2 id="TZif">Other <abbr>TZif</abbr> readers</h2> <ul> <li>The <a href="https://www.gnu.org/software/libc/"><abbr>GNU</abbr> C Library</a> has an independent, thread-safe implementation of -a <code><abbr>tz</abbr></code> binary file reader. +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 <a href="https://developer.gnome.org/glib/">GLib</a> has -a <code><abbr>tz</abbr></code> binary file reader written in C that +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 <code>baltzo::TimeZoneUtil</code> component contains a C++ -implementation of a binary file reader. It is freely available under +implementation of a <abbr>TZif</abbr> file reader. It is freely available under the Apache License.</li> <li><a href="https://github.com/google/cctz">CCTZ</a> is a simple C++ library that translates between <abbr>UT</abbr> and civil time and -can read binary files. It is freely available under the Apache +can read <abbr>TZif</abbr> files. It is freely available under the Apache License.</li> <li><a href="http://bmsi.com/java/#TZ">ZoneInfo.java</a> -is a <code><abbr>tz</abbr></code> binary file reader written in Java. +is a <abbr>TZif</abbr> file reader written in Java. It is freely available under the <abbr>LGPL</abbr>.</li> <li><a href="https://github.com/derickr/timelib">Timelib</a> is a C -library that reads tz binary files and converts +library that reads <abbr>TZif</abbr> files and converts time stamps from one time zone or format to another. It is used by <a href="https://secure.php.net"><abbr title="PHP: Hypertext Preprocessor">PHP</abbr></a>, @@ -465,23 +472,23 @@ It is freely available under the <abbr>MIT</abbr> license.</li> JavaScript library that supports date arithmetic that is time zone aware. It is freely available under the <abbr>MIT</abbr> license.</li> <li>Tcl, mentioned <a href="#Tcl">above</a>, also contains a -<code><abbr>tz</abbr></code> binary file reader.</li> +<abbr>TZif</abbr> file reader.</li> <li><a href="http://search.cpan.org/perldoc?DateTime::TimeZone::Tzfile"> DateTime::TimeZone::Tzfile</a> -is a <code><abbr>tz</abbr></code> binary file reader written in Perl. +is a <abbr>TZif</abbr> file reader written in Perl. It is freely available under the same terms as Perl (dual <abbr>GPL</abbr> and Artistic license).</li> <li>The public-domain <a href="https://github.com/dbaron/tz.js">tz.js</a> library contains a Python tool that -converts <code><abbr>tz</abbr></code> binary data into +converts <abbr>TZif</abbr> data into <abbr>JSON</abbr>-format data suitable for use in its JavaScript library for time zone conversion. Dates before 1970 are not supported.</li> <li>The <a href="https://hackage.haskell.org/package/timezone-olson">timezone-olson</a> package contains <a href="https://www.haskell.org">Haskell</a> code that -parses and uses <code><abbr>tz</abbr></code> binary data. It is freely +parses and uses <abbr>TZif</abbr> data. It is freely available under a <abbr>BSD</abbr>-style license.</li> </ul> <h2 id="software">Other <code><abbr>tz</abbr></code>-based time zone software</h2> diff --git a/zic.c b/zic.c index 0c4c384..f1d0bf3 100644 --- a/zic.c +++ b/zic.c @@ -184,7 +184,7 @@ static bool yearistype(zic_t year, const char * type); enum { PERCENT_Z_LEN_BOUND = sizeof "+995959" - 1 }; /* If true, work around a bug in Qt 5.6.1 and earlier, which mishandles - tz binary files whose POSIX-TZ-style strings contain '<'; see + TZif files whose POSIX-TZ-style strings contain '<'; see QTBUG-53071 <https://bugreports.qt.io/browse/QTBUG-53071>. This workaround will no longer be needed when Qt 5.6.1 and earlier are obsolete, say in the year 2021. */ -- 2.7.4

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[PROPOSED] ‘white-space: pre-wrap’ to avoid tiny fonts
by Paul Eggert May 16, 2018

May 16, 2018

* theory.html, tz-how-to.html, tz-link.html: Use ‘white-space: pre-wrap’ to avoid tiny font on Android mobile browsers. Migrate this style setting to a <style> element, and be consistent about it in the tz web pages. --- theory.html | 3 +++ tz-how-to.html | 3 +++ tz-link.html | 9 ++++++--- 3 files changed, 12 insertions(+), 3 deletions(-) diff --git a/theory.html b/theory.html index 0ada9e3..2d6e505 100644 --- a/theory.html +++ b/theory.html @@ -3,6 +3,9 @@ <head> <title>Theory and pragmatics of the tz code and data</title> <meta charset="UTF-8"> + <style> + pre {margin-left: 2em; white-space: pre-wrap;} + </style> </head> <body> diff --git a/tz-how-to.html b/tz-how-to.html index a54f54a..367c6ed 100644 --- a/tz-how-to.html +++ b/tz-how-to.html @@ -5,6 +5,9 @@ <head> <title>How to Read the tz Database</title> <meta http-equiv="Content-type" content='text/html; charset="UTF-8"'> +<style> +pre {margin-left: 2em; white-space: pre-wrap;} +</style> </head> <body> <h2>How to Read the <a href="https://en.wikipedia.org/wiki/Tz_database">tz diff --git a/tz-link.html b/tz-link.html index b8b7944..87241da 100644 --- a/tz-link.html +++ b/tz-link.html @@ -3,6 +3,9 @@ <head> <title>Sources for time zone and daylight saving time data</title> <meta charset="UTF-8"> +<style> +pre {margin-left: 2em; white-space: pre-wrap;} +</style> </head> <body> <h1>Sources for time zone and daylight saving time data</h1> @@ -97,7 +100,7 @@ href="https://en.wikipedia.org/wiki/Unix_shell">shell</a> commands download 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 style="margin-left: 2em"><code>mkdir tzdb +<pre><code>mkdir tzdb cd tzdb <a href="https://www.gnu.org/software/wget/">wget</a> https://www.iana.org/time-zones/repository/tzcode-latest.tar.gz wget https://www.iana.org/time-zones/repository/tzdata-latest.tar.gz @@ -107,7 +110,7 @@ gzip -dc tzdata-latest.tar.gz | tar -xf - <p>Alternatively, the following shell commands download the same release in a single-tarball format containing extra data useful for regression testing:</p> -<pre style="margin-left: 2em"><code>wget <a href="https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz">https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz</a> +<pre><code>wget <a href="https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz">https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz</a> <a href="https://www.nongnu.org/lzip/">lzip</a> -dc tzdb-latest.tar.lz | tar -xf - </code></pre> <p>These commands use convenience links to the latest release @@ -133,7 +136,7 @@ less-secure protocol.</p> <p>Alternatively, a development repository of code and data can be retrieved from <a href="https://github.com">GitHub</a> via the shell command:</p> -<pre style="margin-left: 2em"><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> <p> Since version 2012e, each release has been tagged in development repositories. -- 2.17.0

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Brazilian Timezone
by Christian Brackmann May 16, 2018

May 16, 2018

Hello! I wonder about the brazilian timezone you call as "America/Sao_Paulo". In Brazil, São Paulo is just a city (with a very large population indeed), but as oficial time in Brazil we use the capital of Brazil, called "Brasília". Why do you use the city of São Paulo as reference? Our legal local time is Brasilia and not São Paulo. Can you please explain it better? Thank you in advance. Best regards. *--* Prof. Dr. Christian Puhlmann Brackmann Coordenador Geral de Pós-Graduação Pró-Reitoria de Pesquisa, Pós-graduação e Inovação Instituto Federal de Educação, Ciência e Tecnologia Farroupilha (IFFAR) brackmann(a)iffarroupilha.edu.br +55 55 3226 6636 / 98100-1819 ** *“Education is the most powerful weapon which you can use to change the world”*Nelson Mandela

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Gripe about compressed rule set names in tzdata.zi
by Tom Lane May 14, 2018

May 14, 2018

Reviewing the changes between 2018d and 2018e crystallized something that had not been clear to me before: the "compressed" ruleset names used in tzdata.zi are chosen as sequential ASCII characters, or pairs of ASCII letters after the single-character names run out. This means that addition or deletion of a ruleset near the beginning of the file creates semantically-insignificant changes throughout the rest of the file, making it hard to review the diffs to get a sense of what changed, or to eyeball-validate the .zi file. It probably also bloats one's repository if storing tzdata.zi in a source code control system. So I'm wondering if it'd be acceptable to change the compression rule to something that gives more stable results. I've not really experimented to see what would work well, but one simple idea is to take the shortest unique prefix of each original ruleset name. There are other options if shortness is prized well above readability. I wouldn't expect the results to be 100% stable in the face of ruleset additions/deletions, since conflicts could appear or disappear, but 99% would be fine. Regardless of the specifics, this would surely have the effect of making tzdata.zi a bit bigger (although compression would likely buy back much of the delta). So, if nobody but me is annoyed by the current behavior, I'd expect such a proposal to get rejected. I'm willing to do the legwork to develop a concrete patch if it'd be likely to get accepted. regards, tom lane

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