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Update documentation.

* tz-link.htm: Prune no-longer-working URLs, update URLs that got
moved, sort a bit.  The most-important casualty is the Norwegian
Meteorological Institute's web page for Summer time in Norway,
formerly at <>: it's
no longer there and I can't find out where it moved to, if
* tzfile.5: Fix minor grammar problem.
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1 parent c7698fd commit ef8095aaf87d98ba5476ac86cff3a160758ed998 @eggert committed Nov 12, 2012
Showing with 63 additions and 112 deletions.
  1. +62 −111 tz-link.htm
  2. +1 −1 tzfile.5
173 tz-link.htm
@@ -8,7 +8,7 @@
<meta http-equiv="Content-type" content='text/html; charset="US-ASCII"'>
<meta name="DC.Creator" content="Eggert, Paul">
<meta name="DC.Contributor" content="Olson, Arthur David">
-<meta name="DC.Date" content="2012-10-28">
+<meta name="DC.Date" content="2012-11-12">
<meta name="DC.Description"
content="Sources of information about time zones and daylight saving time">
<meta name="DC.Identifier"
@@ -101,11 +101,13 @@
The code and data files can also be obtained from the
-<a href="">IANA</a>
-<a href="">timezone web page</a>.
+<a href="">timezone web page</a>
+of the <a href="">Internet Assigned Numbers
+Authority (IANA)</a>.
An <a href="">unofficial development
repository</a> of the code and data is available
-in <a href="">Git</a> form; be careful, as this
+in <a href="">Git</a> form
+from <a href="">GitHub</a>; be careful, as this
repository is less well tested and probably contains more errors.
The code lets you compile the <code>tz</code> source files into
@@ -118,30 +120,19 @@
mailing list</a>. You can also <a
href="">browse recent
messages</a> sent to the mailing list, <a
-href="">subscribe</a> to it.
-browse the <a
+href="">subscribe</a> to it,
+and browse the <a
href="">archive of old
-messages</a> (message by message or in gzip compressed format),
-or retrieve <a
-href="">archived older versions of code
-and data</a>.</p>
The Web has several other sources for time zone and daylight saving time data.
-Here are some recent links that may be of interest.
+Here are some links that may be of interest.
<h2>Web pages using recent versions of the <code>tz</code> database</h2>
These are listed roughly in ascending order of complexity and fanciness.
-<a href="">
-is a service for generating and viewing links that refer to a
-particular point in time and can be displayed in multiple timezones.
-It uses the ruby tzinfo gem.
-(From Tim Diggins, 2009-11-03.)
<li><a href="">Date and Time Gateway</a>
lets you see the <code>TZ</code> values directly.</li>
@@ -151,10 +142,13 @@
uses a pulldown menu.</li>
<li><a href="">Complete
timezone information for all countries</a> displays tables of DST rules.
-<li><a href="">The World Clock -
+<li><a href="">The World Clock &ndash;
Time Zones</a> lets you sort zone names and convert times.</li>
-<li><a href="">Graphical Display of
-Time Zones and Daylight Saving Times</a> shows a graph of time
+<li><a href="">Permatime</a> generates and views
+links that refer to a particular point in time and can be displayed in
+multiple timezones.</li>
+<li><a href="">Daylight Saving Time info</a>
+shows a graph of time
difference versus time for any pair of locations.</li>
<li>The <a href="">World Time Engine</a>
also contains data about time zone boundaries; it supports queries via place
@@ -175,7 +169,7 @@
title="Calendaring and Scheduling Working Group">calsch</abbr>)</a>
covers time zone
data; see its VTIMEZONE calendar component.
-The <a href="">Calendaring and Scheduling
+<a href="">CalConnect, The Calendaring and Scheduling
Consortium</a> is promoting further work in this area. <a
TIMEZONE Problems and Recommendations</a> offers guidelines and
@@ -203,7 +197,7 @@
<h2>Other <code>tz</code> compilers</h2>
-<li><a href="">Vzic iCalendar
+<li><a href="">Vzic iCalendar
Timezone Converter</a> describes a <a
program that compiles
@@ -250,9 +244,9 @@
It is freely available under the <abbr
title="Massachusetts Institute of Technology">MIT</abbr> license.</li>
<li>The <a href="">Chronos Date/Time
-Library</a> is a <a href="">Smalltalk</a> class
-library that compiles <code>tz</code> source into a <a
-href="">time zone repository</a> whose format
+Library</a> is
+a <a href="">Smalltalk</a> class
+library that compiles <code>tz</code> source into a time zone repository whose format
is either proprietary or an <a href=""><abbr
title="Extensible Markup Language">XML</abbr></a>-encoded
@@ -294,7 +288,7 @@
href="">Firefox</a>, <a
href="">Thunderbird</a>, and
It displays multiple clocks in the application window, and has a mapping
interface to <a href="">Google Earth</a>.
It is freely available under the <abbr>GPL</abbr>.</li>
@@ -303,18 +297,17 @@
clock (intclock)</a> is a multi-timezone clock for
<abbr>GNU</abbr>/Linux and similar systems. It is freely available
under the <abbr>GPL</abbr>.</li>
-<li><a href="">PublicDomain</a>
-has a copy of a recent <code>tz</code> database, accessed via a <a
-href="">C#</a> library. As its
-name suggests, it is in the public domain. Only current time stamps
-are well supported; historical data are compiled into the runtime but
-are not easily accessible.</li>
-<li><a href="">Sun Java</a> releases since 1.4
+<li><a href="">Oracle
+Java</a> releases since 1.4
contain a copy of a subset of a recent <code>tz</code> database in a
Java-specific format.</li>
<li><a href="">Time Zone</a> is
a <a href="">WordPress</a> plugin. It is freely
available under a <abbr>BSD</abbr>-style license.</li>
+<li><a href="">Time Zone
+Master</a> is a Microsoft Windows clock program that can automatically
+download, compile and use the <code>tzdata<var>D</var>.tar.gz</code>
+files as they are released. The Basic version is free.</li>
href="">VelaTerra</a> is
a Mac OS X program. Its developers
@@ -323,36 +316,19 @@
href="">World Time Explorer</a> is a
Microsoft Windows program.</li>
-<a href="">
-WorldClock for Windows and Windows Mobile</a>
-lets users "see the time in up to 25 locations in the world at once."
-(From Hans Nieuwenhuis, 2009-11-02.)
-<a href="">
-Time Zone Master Basic
-</a> "allows people to display multiple desktop clocks, and to
-research current and historical time information, as well as times of
-astronomical events (sunrise/transit/set, moonrise/transit/set, phases,
-season starts) for user-selected dates in the past and future. It can
-automatically download, compile and use the tzdata**.gz database files
-as they are released to keep the data up to date. The software is
-free." (Davie Patte)
<h2>Other time zone databases</h2>
<li><a href="">Atlas Query</a>
-is Astrodienst's Web version of Shanks's
-excellent time zone history atlases published in both <a
+is Astrodienst's Web version of Shanks and Pottenger's
+time zone history atlases published in both <a
and book form (<a
-href="">one volume
+href="">one volume
for the USA</a>, and <a
-href="">one for
+href="">one for
other locations</a>) by <a
-href="">Astro Communications Services</a>.</li>
+href="">Astro Computing Services</a>.</li>
<li><a href="">WORLDTIME: interactive atlas,
time info, public holidays</a>
contains information on local time, sunrise and sunset,
@@ -371,28 +347,17 @@
<li>Some Microsoft Windows versions contain time zone information in
an undocumented format, with IDs that can be mapped to <code>TZ</code>
values using the <a
&rarr; Tzid table</a> maintained by the <abbr
title="Common Locale Data Repository">CLDR</abbr> data mentioned
-<a href="">
-provides programming-language-specific representations of timezone
-data. Currently this includes XML, PHP, Ruby, Javascript, JSON and CSV
-formatted data. The repository is updated as soon as the FTP
-distribution is updated. All data can be downloaded as a zip and/or it
-can be obtained/synced via anonymous SVN. Data is made available under
-the MIT license. (From Rich Tibbett.)
<li>The <a href="">United States Central
Intelligence Agency (<abbr
title="Central Intelligence Agency">CIA</abbr>)</a> publishes a <a
zone map</a>; the
@@ -421,9 +386,8 @@
zone boundaries for multizone countries</a> summarizes legal
boundaries between time zones within countries.</li>
<li>'s <a
-href="">Free Maps and
-<abbr title="Geographic Information Systems">GIS</abbr>
-Data</a> includes a Manifold-format map of
+href="">Free Stuff for
+Manifold System Users</a> includes a Manifold-format map of
world time zone boundaries distributed under the
<li>The <abbr>US</abbr> Geological Survey's National Atlas of
@@ -453,15 +417,15 @@
is an overall history of <abbr>DST</abbr>.</li>
<li><a href="">Saving Time,
Saving Energy</a> discusses a primary justification for <abbr>DST</abbr>.</li>
-<li><a href="">Who Knew? A Brief
+<li><a href="">A Brief
History of Daylight Saving Time</a> summarizes some of the contentious
history of <abbr>DST</abbr>.</li>
-<li><a href="">The
+<li><a href="">The
Time of Internet</a>
describes time zones and daylight saving time,
with diagrams.
The time zone map is out of date, however.</li>
-<li><a href="">A History of
+<li><a href="">A History of
the International Date Line</a> tells the story of the most important
time zone boundary.</li>
<li><a href="">Basic Time
@@ -471,7 +435,7 @@
<dd>The Parliamentary Library has commissioned <a
note on daylight saving time in Australia</a>.
The Bureau of Meteorology publishes a list of
<a href="">Implementation Dates of Daylight Savings Time within Australia</a>.</dd>
@@ -485,17 +449,17 @@
hreflang="pt-BR">Brazil's daylight saving time decrees (in
-<dd>The Institute for National Measurement Standards publishes current
+<dd>National Research Council Canada publishes current
and some older information about <a
-Zones &amp; Daylight Saving Time</a>.</dd>
+zones &amp; daylight saving time</a>.</dd>
<dd>The Chilean Hydrographic and Oceanographic Service publishes a <a
href="" hreflang="es"> history of
official time (in Spanish)</a>.</dd>
<dd>The National Institute for Science and Technology maintains the <a
-href="">Realisation of
+href="">Realisation of
Legal Time in Germany</a>.</dd>
<dd>The Interior Ministry periodically issues <a
@@ -509,32 +473,27 @@
<dd>See Singapore below.</dd>
-<dd><a href=""
+<dd><a href=""
hreflang="nl">Legal time in the Netherlands (in Dutch)</a>
covers the history of local time in the Netherlands from ancient times.</dd>
<dt>New Zealand</dt>
-<dd>The Department of Internal Affairs maintains a brief history <a
+<dd>The Department of Internal Affairs maintains a brief <a
+href="">History of
Daylight Saving</a>. The privately-maintained <a
href="">History of New Zealand
time</a> has more details.</dd>
-<dd>The Norwegian Meteorological Institute lists
-<a href="" hreflang="no">Summer
-time in Norway (in Norwegian)</a>, citing the
-Institute of Theoretical Astrophysics, Oslo.</dd>
is Singapore in the "Wrong" Time Zone?</a> details the
history of legal time in Singapore and Malaysia.</dd>
<dt>United Kingdom</dt>
-href="">History of
+href="">History of
legal time in Britain</a> discusses in detail the country
with perhaps the best-documented history of clock adjustments.
The National Physical Laboratory also maintains an <a
of Summer time dates</a>.</dd>
<h2>Precision timekeeping</h2>
@@ -553,7 +512,8 @@
Options for <abbr title="Dynamic Host Configuration Protocol">DHCP</abbr></a>
(Internet <abbr>RFC</abbr> 4833)
specifies a <a
-href="">DHCP</a> option for a server to configure
+option for a server to configure
a client's time zone and daylight saving settings automatically.</li>
<li><a href="">A Few
Facts Concerning <abbr title="Greenwich Mean Time">GMT</abbr>, <abbr
@@ -578,7 +538,7 @@
<abbr title="International Atomic Time">TAI</abbr>,
<abbr>TDB</abbr>, <abbr>TDT</abbr> and
-<li><a href="">Basics of
+<li><a href="">Basics of
Space Flight - Reference Systems - Time Conventions</a>
briefly explains interplanetary space flight timekeeping.</li>
@@ -593,13 +553,9 @@
in general. It covers the state of the art in amateur timekeeping, and
how the art has progressed over the past few decades.</li>
-maintained by the
-<abbr title="International Earth Rotation Service">IERS</abbr>
-<abbr title="Earth Orientation Parameters">EOP</abbr>
-(<abbr title="Product Center">PC</abbr>)</a> contains official publications of
-the Earth Orientation Parameters Product Center of the
-International Earth Rotation Service, the committee that decides
+Bulletins</a> contains official publications of the International
+Earth Rotation and Reference Systems Service, which decides
when leap seconds occur.</li>
<li>The <a
@@ -609,11 +565,8 @@
discussed further in
<a href="">The
leap second: its history and possible future</a>.
-The (now disbanded) <a href=""><abbr
-title="American Astronomical Society">AAS</abbr> Leap Second
-Committee</a> has solicited input on this proposal.
-<a href="">The
-Future of Leap Seconds</a> covers this
+<a href="">UTC might be redefined
+without Leap Seconds</a> gives pointers on this
contentious issue.</li>
<h2>Time notation</h2>
@@ -623,7 +576,7 @@
the International Standard Date and Time Notation</a> is a good
summary of
title="International Organization for Standardization">ISO</abbr>
8601:2004 -- Data elements and interchange formats -- Information
interchange -- Representation of dates and times</a>.</li>
@@ -658,8 +611,8 @@
French translations for "Eastern European Summer Time", "<abbr
title="Eastern European Summer Time">EEST</abbr>", and
"Bucharest". <a
-Chart: names.metazone</a> shows these values for many locales.
+Chart</a> shows these values for many locales.
<abbr>ICU</abbr> contains a mechanism for using this data.</li>
<li>Alphabetic time zone abbreviations should not be used as unique
identifiers for <abbr>UTC</abbr> offsets as they are ambiguous in
@@ -693,8 +646,6 @@
<li><a href="tz-art.htm">Time and the Arts</a></li>
<li><a href="">Open Directory -
Reference: Time</a></li>
-<li><a href="">Google Directory
-- Reference &gt; Time</a></li>
<li><a href="">Yahoo!
Directory &gt; Science &gt; Measurements and Units &gt; Time</a></li>
2 tzfile.5
@@ -137,7 +137,7 @@ is zero or the time argument is less than the first transition time recorded
in the file.
For version-2-format time zone files,
-the above header and data is followed by a second header and data,
+the above header and data are followed by a second header and data,
identical in format except that
eight bytes are used for each transition time or leap second time.
After the second header and data comes a newline-enclosed,

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