May 2018 - tz - lists.iana.org

[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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new mailing list: tzdist-bis@ietf.org
by Eliot Lear May 11, 2018

May 11, 2018

Hello everyone, I would like to bring to your attention two drafts that we have formed a mailing list around two drafts: draft-murchison-tzdist-geolocate-01 The Time Zone Data Distribution Service (TZDIST) Geolocate Extension The basic idea behind this draft is, given a geo: URI, please provide provide an appropriate TZID. And draft-murchison-tzdist-tzif-00 The Time Zone Information Format (TZif) This document is the one I've been waiting for a long time: it describes the format that those tz files have been using, and it features as co-authors Paul Eggert and Arthur David Olson. The intent is to do a sort of micro-wg to get both of these docs turned into RFCs. To do that, we need good reviewers, particularly ones who have previously cracked and parsed the tz files (bonus points if you were crazy enough to write out one!!). There is a mailing list for this purpose: tzdist-bis(a)ietf.org. You can join it by going to https://www.ietf.org/mailman/listinfo/tzdist-bis. I look forward to seeing a few of you over there (you know who you are). Eliot

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Time in Macau
by P Chan May 10, 2018

May 10, 2018

Hi, I would like to share some information about the history of time in Macau. All the sources I used can be accessed online. LegisMac http://legismac.safp.gov.mo/legismac/descqry/Descqry.jsf?lang=pt A database for searching titles of legal documents of Macau in Chinese and Portuguese. The term "HORÁRIO DE VERÃO" can be used for searching decrees about summer time. Archives of Macao http://www.archives.gov.mo/en/bo/ It contains images of old official gazettes. The Macao Meteorological and Geophysical Bureau have a page listing the summer time history. But it is not complete and has some mistakes. <http://www.smg.gov.mo/smg/geophysics/c_t_Summer%20Time.htm>http://www.smg.gov.mo/smg/geophysics/e_t_Summer%20Time.htm Macau adopted GMT+8 on 30 Oct 1904 to follow Hong Kong. Clocks were advanced by 25 minutes and 50 seconds. Which means the LMT used was +7:34:10. As stated in the "Portaria N.º 204" dated 21 October 1904 and published in the Official Gazette on 29 October 1904. http://igallery.icm.gov.mo/Images/Archives/BO/MO_AH_PUB_BO_1904_10/MO_AH_PU… Therefore the 1911 decree of Portugal did not change time in Macau. >From LegisMac, here is a list of decrees that changed the time. Decree Gazette no. Gazette date Title DIL 732 BOCM 51 1941.12.20 adoptando medidas excepcionais que garantam o funcionamento de todos os serviços públicos e particulares e restringindo ao mínimo o consumo de alguns géneros e artigos essenciais à vida da colónia. DIL 764 BOCM 9S 1942.04.30 Determinando que sejam adiantadas de uma hora os relógios da colónia e regulando os horários das repartições públicas. DIL 781 BOCM 21 1942.10.10 Substituindo o corpo do artigo 3° do diploma legislativo n° 732 e suas alíneas a) e b), respeitantes às alterações da hora e horário das Repartições Públicas, e revogando o diploma legislativo n° 764. PT 3434 BOCM 8S 1943.04.17 determinando que às 23 horas do dia 30 do corrente mês sejam adiantadas de uma hora os relógios da colónia e regulando o horário das Repartições Públicas. PT 3504 BOCM 20 1943.09.25 regulando o horário das Repartições Públicas e determinando que no dia 30 do corrente, às 23 horas, os relógios sejam atrasados de uma hora. PT 3843 BOCM 39 1945.09.29 regulando o horário das Repartições Públicas e determinando que no dia 30 do corrente, às 24 horas, os relógios sejam atrasados de uma hora. PT 3961 BOCM 17 1946.04.27 Determinando que, a partir das 23 horas do dia 30 do corrente mês, sejam adiantados de uma hora os relógios da Colónia. PT 4026 BOCM 39 1946.09.28 estabelecendo o horário da Repartições Públicas e determinando que no dia 30 do corrente, às 24 horas, os relógios sejam atrasados de uma hora. PT 4153 BOCM 16 1947.04.10 Determinando que, a partir das 23 horas do dia 19 do corrente mês, sejam adiantados de uma hora os relógios da Colónia. PT 4271 BOCM 48 1947.11.29 Determinando que, a aprtir do dia 30 do corrente às 24 horas, os relógios sejam atrasados de uma hora. PT 4374 BOCM 18 1948.05.01 Determina que, a partir das 23 horas do dia 2 do corrente mês, sejam adiantados de uma hora os relógios de Colónia. PT 4465 BOCM 44 1948.10.30 Determina que no dia 31 do corrente mês, às 24 horas, os relógios sejam atrasados de uma hora. PT 4590 BOCM 14 1949.04.02 Determina que, a partir das 23 horas do dia 2 do corrente mês, sejam adiantados de uma hora os relógios da Colónia. PT 4666 BOCM 44 1949.10.29 Determina que no dia 30 do corrente, a 0 hora, os relógios sejam atrasados de uma hora. PT 4771 BOCM 12 1950.03.25 Determina que, a partir das 23 horas do dia 1 do próximo mês de Abril, serão adiantados de uma horas os relógios da Colónia. PT 4838 BOCM 43 1950.10.28 Determina que no dia 28 do corrente, às 24 horas, os relógios sejam atrasados de uma hora. PT 4946 BOCM 12 1951.03.24 Determina que, a partir das 23 horas do dia 31 de Março do corrente ano, serão adiantados de uma hora os relógios desta colónia. PT 5025 BO 43 1951.10.27 Manda que no dia 29 do corrente, às zero horas, os relógios sejam atrasados de uma hora. PT 5149 BO 14 1952.04.05 Determina que a partir das 23 horas do dia 5 de Abril corrente serão adiantados de uma hora os relógios desta província. PT 5251 BO 43 1952.10.25 Determina que no dia 2 do próximo mês de Novembro, às zero horas, os relógios serão atrasados de uma hora. PT 5366 BO 13 1953.03.28 Determina que a partir das 23 horas do dia 4 do próximo mês de Abril serão adiantados de uma hora os relógios desta província. PT 5444 BO 44 1953.10.31 Determina que no dia 31 do corrente, às 24 horas, os relógios sejam atrasados de uma hora. PT 5540 BO 12 1954.03.20 Determina que, a partir das 23 horas de hoje, serão adiantados de uma hora os relógios da Província. PT 5589 BO 44 1954.10.30 Determina que, a partir das 24,00 horas de hoje, 30 do corrente, os relógios sejam atrasados de uma hora. PT 5676 BO 12 1955.03.19 Manda adiantar de uma hora os relógios da Província, a partir das 23 horas de hoje, 19 do corrente. PT 5739 BO 45 1955.11.05 Determina que às 24,00 horas de hoje, 5 de corrente, os relógios sejam atrasados de uma hora. PT 5823 BO 11 1956.03.17 Determina que a partir das 23 horas de hoje, 17 do corrente, serão adiantados de uma hora os relógios da Província. PT 5891 BO 44 1956.11.03 Determina que no dia 4 do corrente mês, às 3 horas e 30 minutos, os relógios sejam atrasados de uma hora. PT 5981 BO 12 1957.03.23 Determina que, a partir das 3,30 horas do dia 24 do corrente mês, sejam adiantados de uma hora os relógios da Província. PT 6064 BO 43 1957.10.26 Determina que no dia 3 do próximo mês do Novembro, às 3 horas e 30 minutos, os relógios sejam atrasados de uma hora. PT 6172 BO 12 1958.03.22 Determina que, a partir das 3,30 horas do dia 23 do corrente mês, sejam adiantados de uma hora os relógios da Província. PT 6243 BO 43 1958.10.25 Determina que no dia 2 do próximo mês do Novembro, às 3 horas e 30 minutos, os relógios sejam atrasados de uma hora. PT 6341 BO 12 1959.03.21 Determina que, a partir das 3,30 horas do dia 22 do corrente, sejam adiantados de uma hora os relógios da Província. PT 6411 BO 43 1959.10.24 Determina que no dia 1 do próximo mês de Novembro, às 3 horas e 30 minutos, os relógios sejam atrasados de uma hora. PT 6514 BO 11 1960.03.12 Determina que, a partir das 3,30 horas do dia 20 do corrente, sejam adiantados de uma hora os relógios da Província. PT 6584 BO 44 1960.10.29 Determina que no dia 6 do próximo mês de Novembro, às 3,30 horas, os relógios sejam atrasados de uma hora. PT 6721 BO 10 1961.03.11 Determina que, a partir das 3,30 horas do dia 19 do corrente, sejam adiantados os relógios da Província. PT 6815 BO 43 1961.10.28 Determina que no dia 5 do próximo mês de Novembro, às 3,30 horas, os relógios sejam atrasados de uma hora. PT 6947 BO 10 1962.03.10 Determina que a partir das 3,30 horas do dia 18 do corrente, sejam adiantados de uma hora os relógios da província. PT 7080 BO 43 1962.10.27 Determina que no dia 4 do próximo mês de Novembro, às 3,30 horas, os relógios sejam atrasados de uma hora. PT 7218 BO 12 1963.03.23 Determina que a partir das 3,30 horas do dia 24 do corrente, sejam adiantados de uma hora os relógios de província. PT 7340 BO 43 1963.10.26 Detremina que a partir da 3,30 horas do dia 3 do próximo mês de Novembro, sejam atrasados de uma hora os relógios da província. PT 7491 BO 11 1964.03.14 Determina que a partir das 3,30 horas do dia 22 do corrente, os relógios sejam adiantados uma hora. PT 7664 BO 43 1964.10.24 Determina que a partir das 3,30 horas do dia 1 do próximo mês de Novembro, sejam atrasados de uma hora os relógios da província. PT 7846 BO 15 1965.04.10 Determina que a partir das 3,30 horas do dia 18 do corrente, os relógios sejam adiantados de uma hora. PT 7979 BO 42 1965.10.16 Determina que, a partir das 2,30 horas do próximo dia 17 do corrente, sejam atrasados de uma hora os relógios da província. PT 8146 BO 15 1966.04.09 Determina que os relógios da província sejam adiantados de uma hora, a partir das 3,30 horas do dia 17 do corrente. PT 8252 BO 41 1966.10.08 Determina que, às 2,30 horas do dia 16 do corrente, os relógios sejam atrasados de uma hora. PT 8429 BO 15 1967.04.15 Manda que no dia 16 do corrente, às 3,30 horas, os relógios sejam adiantados de uma hora. PT 8540 BO 41 1967.10.14 Manda que, no próximo dis 22 do corrente, às 3,30 horas, os relógios sejam atrasados de uma hora. PT 8735 BO 15 1968.04.13 Manda que no dia 21 do corrente, às 3,30 horas, os relógios sejam adiantados de uma hora. PT 8860 BO 41 1968.10.12 Manda que, no próximo dia 20 do corrente, às 3,30 horas, os relógios sejam atrasados de uma hora. PT 9035 BO 16 1969.04.19 Manda que no dia 20 do corrente, às 3,30 horas, os relógios sejam adiantados de uma hora. PT 9156 BO 42 1969.10.18 Manda que no dia 19 do corrente, às relógios sejam atrasados de uma hora. PT 9328 BO 15 1970.04.11 Manda que no dia 19 do corrente às 3,30 horas, os relógios sejam adiantados de uma hora. PT 9418 BO 41 1970.10.10 Manda que no dia 18 do corrente, às 3,30 horas, os relógios sejam atrasados de uma hora. PT 9587 BO 14 1971.04.03 Manda que no dia 18 do corrente, às 3,30 horas, os relógios sejam adiantados de uma hora. PT 9702 BO 41 1971.10.09 Manda que no dia 17 do corrente, às 3,30 horas, os relógios sejam atrasados de uma hora. PT 38-A/72 BO 14 1972.04.01 Manda que no dia 16 do corrente, às 3,30 horas, os relógios sejam adiantados de uma hora. PT 126-A/72 BO 41 1972.10.07 Manda que no dia 22 do corrente, às 3,30 horas, os relógios sejam atrasados de uma hora. PT 61/73 BO 14 1973.04.07 Manda que no dia 22 do corrente, às 3,30 horas, os relógios sejam adiantados de uma hora. PT 182/73 BO 40 1973.10.06 Manda que no dia 21 do corrente, às 3.30 horas, os relógios sejam atrasados de uma hora. PT 282/73 BO 51 1973.12.22 Manda que no dia 30 do corrente mês de Dezembro, às 3,30 horas, os relógios sejam adiantados de uma hora. PT 177/74 BO 41 1974.10.12 Manda que no dia 20 do corrente, às 3,30 horas, os relógios sejam atrasados de uma hora. PT 51/75 BO 15 1975.04.12 Manda que no dia 20 do corrente, às 3,30 horas, os relógios sejam adiantados de uma hora. PT 173/75 BO 41 1975.10.11 Manda que no dia 19 do corrente mês, às 3,30 horas, os relógios sejam atrasados de uma hora. PT 67/76/M BO 14 1976.04.03 Manda que no dia 18 de Abril do corrente ano, às 3,30 horas, os relógios sejam adiantados de uma hora. PT 169/76/M BO 41 1976.10.09 Manda que, no dia 17 de Outubro corrente, às 3,30 horas, os relógios, sejam atrasados de uma hora. PT 78/79/M BO 19 1979.05.12 Manda que, no dia 13 de Maio de 1979, os relógios sejam adiantados de uma hora. PT 166/79/M BO 42 1979.10.20 Manda que, no dia 21 de Outubro de 1979, os relógios sejam atrasados de uma hora. Note that DIL 732 does not belong to "HORÁRIO DE VERÃO" according to LegisMac. Here is a list of time change according to the decrees, each change corresponds to each decree. Date Time Change 1941-12-21 Sun 2300 +1 1942-04-30 Thu 2300 +1 1942-11-17 Tue 2300 -1 1943-04-30 Fri 2300 +1 1943-09-30 Thu 2300 -1 1945-09-30 Sun 2400 -1 1946-04-30 Tue 2300 +1 1946-09-30 Mon 2400 -1 1947-04-19 Sat 2300 +1 1947-11-30 Sun 2400 -1 1948-05-02 Sun 2300 +1 1948-10-31 Sun 2400 -1 1949-04-02 Sat 2300 +1 1949-10-30 Sun 0000 -1 1950-04-01 Sat 2300 +1 1950-10-28 Sat 2400 -1 1951-03-31 Sat 2300 +1 1951-10-29 Mon 0000 -1 1952-04-05 Sat 2300 +1 1952-11-02 Sun 0000 -1 1953-04-04 Sat 2300 +1 1953-10-31 Sat 2400 -1 1954-03-20 Sat 2300 +1 1954-10-30 Sat 2400 -1 1955-03-19 Sat 2300 +1 1955-11-05 Sat 2400 -1 1956-03-17 Sat 2300 +1 1956-11-04 Sun 0330 -1 1957-03-24 Sun 0330 +1 1957-11-03 Sun 0330 -1 1958-03-23 Sun 0330 +1 1958-11-02 Sun 0330 -1 1959-03-22 Sun 0330 +1 1959-11-01 Sun 0330 -1 1960-03-20 Sun 0330 +1 1960-11-06 Sun 0330 -1 1961-03-19 Sun 0330 +1 1961-11-05 Sun 0330 -1 1962-03-18 Sun 0330 +1 1962-11-04 Sun 0330 -1 1963-03-24 Sun 0330 +1 1963-11-03 Sun 0330 -1 1964-03-22 Sun 0330 +1 1964-11-01 Sun 0330 -1 1965-04-18 Sun 0330 +1 1965-10-17 Sun 0230 -1 1966-04-17 Sun 0330 +1 1966-10-16 Sun 0230 -1 1967-04-16 Sun 0330 +1 1967-10-22 Sun 0330 -1 1968-04-21 Sun 0330 +1 1968-10-20 Sun 0330 -1 1969-04-20 Sun 0330 +1 1969-10-19 Sun 0330 -1 1970-04-19 Sun 0330 +1 1970-10-18 Sun 0330 -1 1971-04-18 Sun 0330 +1 1971-10-17 Sun 0330 -1 1972-04-16 Sun 0330 +1 1972-10-22 Sun 0330 -1 1973-04-22 Sun 0330 +1 1973-10-21 Sun 0330 -1 1973-12-30 Sun 0330 +1 1974-10-20 Sun 0330 -1 1975-04-20 Sun 0330 +1 1975-10-19 Sun 0330 -1 1976-04-18 Sun 0330 +1 1976-10-17 Sun 0330 -1 1979-05-13 Sun 0330 +1 1979-10-21 Sun 0330 -1 Note that between 1942 and 1945, the time switched between GMT+9 and GMT+10. Also in 1965 and 1965 the DST ended at 2:30am. I actually don't speak Portuguese, please correct me if I'm wrong. Regards, P Chan

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'Pyongyang Time' scrapped as North Korea synchronises clocks with the South
by Kim Sungwoo May 9, 2018

May 9, 2018

Hello, I am Sungwoo Kim, leave in Seoul, Republic of Korea. (South Korea) Since 5. 5. 2018, Pyongyang Time - North Korea time - had synchronized with South. We should discussion how we can synchronize PYT to KST with less side-effect. Here is articles include more information and backgrounds. https://www.telegraph.co.uk/news/2018/05/05/pyongyang-time-scrapped-north-k… http://www.xinhuanet.com/english/2018-05/05/c_137158132.htm http://calgarysun.com/news/world/no-more-pyongyang-time-north-korea-changes… https://qz.com/1265352/north-korea-will-reunifying-its-time-zone-with-south…

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China DST
by chan jason May 7, 2018

May 7, 2018

Hi, There are some mistakes in the rules of PRC. The start and end time of DST in China should be 2:00 (i.e. 2:00 to 3:00 at the start and 2:00 to 1:00 at the end). Also in 1988, the start date should be 17 May instead of 10 May. Government notices about summer time: 1986-04-12 http://www.zj.gov.cn/attach/zfgb/198608.pdf p.21-22 (To establish summer time from 1986. On 4 May, set the clocks ahead one hour at 2 am. On 14 September, set the clocks backward one hour at 2 am.) 1987-02-15 http://www.gov.cn/gongbao/shuju/1987/gwyb198703.pdf p.114 (Summer time in 1987 to start from 12 April until 13 September) 1987-09-09 http://www.gov.cn/gongbao/shuju/1987/gwyb198721.pdf p.709 (From 1988, summer time to start from 2 am of the first Sunday of mid-April until 2 am of the first Sunday of mid-September) 1992-03-03 http://www.gov.cn/gongbao/shuju/1992/gwyb199205.pdf p.152 (To suspend summer time from 1992) The first page of People's Daily on 12 April 1988 stating that summer time to begin on 17 April. http://data.people.com.cn/pic/101p/1988/04/1988041201.jpg Proposed rules: Rule PRC 1986 only - May 4 2:00 1:00 D Rule PRC 1986 1991 - Sep Sun>=11 2:00 0 S Rule PRC 1987 1991 - Apr Sun>=11 2:00 1:00 D Regards, P Chan

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Update for tz-how-to.html?
by Kerry Shetline May 6, 2018

May 6, 2018

Could we get an update to the tz-how-to.html document which: 1) Explains how to parse tzdata files for vanguard, rearguard, and standard versions? It looks like the way vanguard sections are not commented out, and rearguard sections are, that any third-party parser for tzdata is going to pick up vanguard zones and rules by default, rather than main. What I’d like to know how to parse the tzdata files, directly as they are found in a standard distribution, with rearguard, main, or vanguard results in mind, and without to run "make tarballs” to get a specific version. 2) Demonstrates the usage of the new ’s' and ‘d' suffixes in SAVE columns? Any help with these issues would be much appreciated. -Kerry

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