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<meta http-equiv="Content-type" content='text/html; charset="US-ASCII"'>
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<meta name="DC.Creator" content="Eggert, Paul">
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<meta name="DC.Contributor" content="Olson, Arthur David">
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<meta name="DC.Date" content="2007-08-17">
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<meta name="DC.Date" content="2007-12-26">
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<meta name="DC.Description"
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content="Sources of information about time zones and daylight saving time">
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<meta name="DC.Identifier" content="http://www.twinsun.com/tz/tz-link.htm">
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C Library</a> used in
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<a href="http://www.linux.org/"><abbr>GNU</abbr>/Linux</a>,
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<a href="http://www.freebsd.org/">FreeBSD</a>,
48
<a href="http://www.netbsd.org/">NetBSD</a>,
49
<a href="http://www.openbsd.org/">OpenBSD</a>,
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<a href="http://www.cygwin.com/">Cygwin</a>,
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<a href="http://netbsd.org/">NetBSD</a>,
49
<a href="http://openbsd.org/">OpenBSD</a>,
50
<a href="http://cygwin.com/">Cygwin</a>,
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<a href="http://www.delorie.com/djgpp/"><abbr
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title="DJ's GNU Programming Platform">DJGPP</abbr></a>,
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<a href="http://www.ibm.com/servers/aix/">AIX</a>,
53
<a href="http://ibm.com/aix">AIX</a>,
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<a href="http://www.apple.com/macosx/">Mac OS X</a>,
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<a href="http://h71000.www7.hp.com/">OpenVMS</a>,
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<a href="http://www.oracle.com/database/index.html">Oracle Database</a>,
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<a href="http://www.sun.com/software/solaris/">Solaris</a>,
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<a href="http://oracle.com/database">Oracle Database</a>,
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<a href="http://sun.com/software/solaris">Solaris</a>,
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<a href="http://h30097.www3.hp.com/">Tru64</a>, and
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<a href="http://www.sco.com/products/unixware/">UnixWare</a>.</p>
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<a href="http://sco.com/products/unixware">UnixWare</a>.</p>
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Each location in the database represents a national region where all
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clocks keeping local time have agreed since 1970.
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the location's full name, e.g., <code>TZ="America/New_York"</code>.</p>
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In the <code>tz</code> database's
82
<a href="ftp://elsie.nci.nih.gov/pub/"><abbr
82
<a href="ftp://elsie.nci.nih.gov/pub"><abbr
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title="File Transfer Protocol">FTP</abbr> distribution</a>
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the code is in the file <code>tzcode<var>C</var>.tar.gz</code>,
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where <code><var>C</var></code> is the code's version;
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similarly, the data are in <code>tzdata<var>D</var>.tar.gz</code>,
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where <code><var>D</var></code> is the data's version.
88
The following shell commands download
89
href="http://en.wikipedia.org/wiki/Unix_shell">shell</a> commands download
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these files to a <abbr>GNU</abbr>/Linux or similar host;
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<code>README</code> file for what to do next.</p>
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The data are by no means authoritative. If you find errors, please
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send changes to the <a href="mailto:tz@elsie.nci.nih.gov">time zone
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mailing list</a>. You can also <a
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href="http://news.gmane.org/gmane.comp.time.tz/">browse recent
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href="http://news.gmane.org/gmane.comp.time.tz">browse recent
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messages</a> sent to the mailing list, <a
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href="mailto:tz-request@elsie.nci.nih.gov">subscribe</a> to it,
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href="ftp://elsie.nci.nih.gov/pub/tzarchive.gz">full archive of old
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messages</a> (in gzip compressed format), or retrieve <a
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href="ftp://munnari.oz.au/pub/oldtz/">archived older versions of code
112
href="ftp://munnari.oz.au/pub/oldtz">archived older versions of code
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and data</a>; there is also a smaller <a
113
href="http://public.planetmirror.com/pub/timezone/"><abbr
114
href="http://public.planetmirror.com/pub/timezone"><abbr
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title="Hypertext Transfer Protocol">HTTP</abbr>
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Here are some recent links that may be of interest.
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<h2>Web pages using recent versions of the <code>tz</code> database</h2>
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These are listed roughly in ascending order of complexity and fanciness.
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<li><a href="http://twiki.org/cgi-bin/xtra/tzdatepick.html">Date and Time Gateway</a>
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is a text-based point-and-click interface to tables of current time
124
throughout the world.</li>
125
<li>Fancier web interfaces, roughly in ascending order of complexity, include:
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lets you see the <code>TZ</code> values directly.</li>
128
href="http://www.convertit.com/Go/ConvertIt/World_Time/Current_Time.ASP">Current
129
Time in 1000 Places</a></li>
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<li><a href="http://timezoneconverter.com/">Time Zone Converter</a></li>
129
href="http://convertit.com/Go/ConvertIt/World_Time/Current_Time.ASP">Current
130
Time in 1000 Places</a> uses descriptions of the values.</li>
131
<li><a href="http://www.timezoneconverter.com/">Time Zone Converter</a>
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uses a pulldown menu.</li>
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<li><a href="http://home.tiscali.nl/~t876506/TZworld.html">Complete
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timezone information for all countries</a></li>
134
<li><a href="http://www.timeanddate.com/worldclock/">The World Clock -
136
is a web interface to a time zone database derived from
137
<code>tz</code>'s.</li>
134
timezone information for all countries</a> displays tables of DST rules.
135
<li><a href="http://timeanddate.com/worldclock/">The World Clock -
136
Time Zones</a> lets you sort zone names and convert times.</li>
137
<li>The <a href="http://worldtimeengine.com/">World Time Engine</a>
138
also contains data about time zone boundaries; it supports queries via place
139
names and shows location maps.</li>
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<h2>Other time zone database formats</h2>
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<li>The <a href="ftp://ftp.rfc-editor.org/in-notes/rfc2445.txt">
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Internet Calendaring and Scheduling Core Object Specification
143
(iCalendar)</a> specification published by the (now-concluded) <a
144
href="http://www.ietf.org/html.charters/OLD/calsch-charter.html"><abbr
145
(iCalendar)</a>, Internet <abbr title="Request For
146
Comments">RFC</abbr> 2445, published by the (now-concluded) <a
147
href="http://ietf.org/html.charters/OLD/calsch-charter.html"><abbr
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title="Internet Engineering Task Force">IETF</abbr>
146
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Calendaring and Scheduling Working Group (<abbr
147
150
title="Calendaring and Scheduling Working Group">calsch</abbr>)</a>
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data; see its VTIMEZONE calendar component.
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The <a href="http://www.calconnect.org/">Calendaring and Scheduling
153
The <a href="http://calconnect.org/">Calendaring and Scheduling
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Consortium</a> is promoting further work in this area. <a
152
href="http://www.calconnect.org/publications/icalendartimezoneproblemsandrecommendationsv1.0.pdf">iCalendar
155
href="http://calconnect.org/publications/icalendartimezoneproblemsandrecommendationsv1.0.pdf">iCalendar
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TIMEZONE Problems and Recommendations</a> offers guidelines and
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recommendations for the use of VTIMEZONE and <code>tz</code>.</li>
155
<li><a href="http://www.calconnect.org/dstlinks.html">Extended Daylight
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<li><a href="http://calconnect.org/dstlinks.shtml">Extended Daylight
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159
Saving Time Links, Advisories and Changes</a> lists vendor material on recent
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daylight saving time changes.</li>
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href="http://www.calconnect.org/publications/timezoneregistryandservicerecommendationsv1.0.pdf">Timezone
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href="http://calconnect.org/publications/timezoneregistryandservicerecommendationsv1.0.pdf">Timezone
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Registry and Service Recommendations</a> discusses a
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strategy for defining and deploying a time zone
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registration process that would establish unique names for each
185
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href="http://www.gnu.org/copyleft/gpl.html"><abbr>GNU</abbr>
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General Public License (<abbr
187
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title="General Public License">GPL</abbr>)</a>.</li>
188
<li><a href="http://sourceforge.net/projects/tzical/">tziCal - tz
191
<li><a href="http://sourceforge.net/projects/tzical">tziCal - tz
189
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database conversion utility</a> is like Vzic, except for the <a
190
href="http://msdn.microsoft.com/netframework/">.NET framework</a>.</li>
193
href="http://msdn.microsoft.com/netframework">.NET framework</a>.</li>
192
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href="http://search.cpan.org/dist/DateTime-TimeZone/">DateTime::TimeZone</a>
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contains a script <code>parse_olson</code> that compiles
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License. DateTime::TimeZone also contains a script
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<code>tests_from_zdump</code> that generates test cases for each clock
200
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transition in the <code>tz</code> database.</li>
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<li><a href="http://icu-project.org/"><abbr
202
title="International Components for Unicode">ICU</abbr></a>
203
contains a C/C++ library for internationalization that
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<li><a href="http://icu-project.org/">International Components for
205
Unicode (<abbr>ICU</abbr>)</a> contains C/C++ and <a
206
href="http://en.wikipedia.org/wiki/Java_%28programming_language%29">Java</a>
207
libraries for internationalization that
204
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has a compiler from <code>tz</code> source
205
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into an <abbr>ICU</abbr>-specific format.
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<abbr>ICU</abbr> is freely available under a
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<code>org.joda.time.tz.ZoneInfoCompiler</code> that compiles
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<code>tz</code> source into a Joda-specific binary format. Joda Time
213
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is freely available under a <abbr>BSD</abbr>-style license.</li>
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<li><a href="http://mozware.free.fr/devtools/xmlDate/">xmlDate</a>
216
href="http://en.wikipedia.org/wiki/JavaScript">JavaScript</a> code that
217
parses <samp>tz</samp> source into an internal object that represents
218
a time zone. It is freely available under the GPL.</li>
219
<li><a href="http://sourceforge.net/projects/pytz/">PyTZ - Python Time
218
<li><a href="http://sourceforge.net/projects/pytz">PyTZ - Python Time
220
219
Zone Library</a> compiles <code>tz</code> source into
221
<a href="http://www.python.org/">Python</a>.
220
<a href="http://python.org/">Python</a>.
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It is freely available under a <abbr>BSD</abbr>-style license.</li>
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<li><a href="http://tzinfo.rubyforge.org/">TZInfo - Ruby Timezone Library</a>
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compiles <code>tz</code> source into
225
<a href="http://www.ruby-lang.org/">Ruby</a>.
224
<a href="http://ruby-lang.org">Ruby</a>.
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It is freely available under the <abbr
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title="Massachusetts Institute of Technology">MIT</abbr> license.</li>
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<li>The <a href="http://www.chronos-st.org/">Chronos Date/Time
229
Library</a> is a <a href="http://smalltalk.org/">Smalltalk</a> class
227
<li>The <a href="http://chronos-st.org/">Chronos Date/Time
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Library</a> is a <a href="http://smalltalk.org">Smalltalk</a> class
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library that compiles <code>tz</code> source into a <a
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href="http://date-time-zone.com/">time zone repository</a> whose format
232
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is either proprietary or an <a href="http://www.w3.org/XML/"><abbr
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232
title="Extensible Markup Language">XML</abbr></a>-encoded
234
233
representation.</li>
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<li>Starting with version 8.5, <a href="http://www.tcl.tk/">Tcl</a>
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<li>Starting with version 8.5, <a href="http://tcl.tk/">Tcl</a>
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contains a developer-oriented parser that compiles <samp>tz</samp>
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236
source into text files, along with a runtime that can read those
238
237
files. Tcl is freely available under a <abbr>BSD</abbr>-style
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<abbr>GNU</abbr> Lesser General Public License
251
250
(<abbr title="Lesser General Public License">LGPL</abbr>)</a>,
252
251
and is widely used in <abbr>GNU</abbr>/Linux systems.</li>
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<li><a href="http://www.bmsi.com/java/#TZ">ZoneInfo.java</a>
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is a <code>tz</code> binary file reader written in <a
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href="http://en.wikipedia.org/wiki/Java_%28programming_language%29">Java</a>.
252
<li><a href="http://bmsi.com/java/#TZ">ZoneInfo.java</a>
253
is a <code>tz</code> binary file reader written in Java.
256
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It is freely available under the <abbr>LGPL</abbr>.</li>
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<li>Tcl, mentioned above, also contains a
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<code>tz</code> binary file reader.</li>
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<h2>Other <code>tz</code>-based time zone software</h2>
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<li><a href="http://www.stemhaus.com/firefox/foxclocks/">FoxClocks</a>
260
<li><a href="http://stemhaus.com/firefox/foxclocks/">FoxClocks</a>
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is an extension for <a
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href="http://developer.mozilla.org/en/docs/Toolkit_API">Mozilla
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Toolkit</a> applications like <a
266
href="http://www.mozilla.com/firefox/">Firefox</a>, <a
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href="http://www.mozilla.com/en-US/thunderbird/">Thunderbird</a>, and
264
href="http://mozilla.com/firefox">Firefox</a>, <a
265
href="http://mozilla.com/thunderbird">Thunderbird</a>, and
269
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href="http://www.mozilla.org/projects/calendar/sunbird/">Sunbird</a>.
270
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It displays multiple clocks in the application window, and has a mapping
275
273
clock (intclock)</a> is a multi-timezone clock for
276
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<abbr>GNU</abbr>/Linux and similar systems. It is freely available
277
275
under the <abbr>GPL</abbr>.</li>
278
<li><a href="http://www.codeplex.com/publicdomain">PublicDomain</a>
276
<li><a href="http://codeplex.com/publicdomain">PublicDomain</a>
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has a copy of a recent <code>tz</code> database, accessed via a <a
280
278
href="http://en.wikipedia.org/wiki/C_Sharp">C#</a> library. As its
281
279
name suggests, it is in the public domain. Only current time stamps
288
286
a <a href="http://wordpress.org/">WordPress</a> plugin. It is freely
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available under a <abbr>BSD</abbr>-style license.</li>
291
href="http://www.veladg.com/velaterra.html">VelaTerra</a> is
289
href="http://veladg.com/velaterra.html">VelaTerra</a> is
292
290
a Mac OS X program. Its developers
293
<a href="http://www.veladg.com/tzoffer.html">offer free
291
<a href="http://veladg.com/tzoffer.html">offer free
294
292
licenses</a> to <code>tz</code> contributors.</li>
296
href="http://www.worldtimeexplorer.com/index.html">World Time Explorer</a> is a
294
href="http://worldtimeexplorer.com/">World Time Explorer</a> is a
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Microsoft Windows program.</li>
299
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<h2>Other time zone databases</h2>
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time info, public holidays</a>
313
311
contains information on local time, sunrise and sunset,
314
312
and public holidays in several hundred cities around the world.</li>
315
<li><a href="http://www.worldtimeserver.com/">World Time Server</a>
313
<li><a href="http://worldtimeserver.com/">World Time Server</a>
316
314
is another time zone database.</li>
317
315
<li><a href="http://tycho.usno.navy.mil/tzones.html">World Time Zones</a>
318
316
contains data from the Time Service Department of the
319
317
<abbr>US</abbr> Naval Observatory, used as the source
320
318
for the <code>usno*</code> files in the <code>tz</code> distribution.</li>
321
<li>The <a href="http://www.iata.org/ps/publications/9179.htm">Standard
319
<li>The <a href="http://iata.org/ps/publications/SSIM.htm">Standard
322
320
Schedules Information Manual</a> of the
323
<a href="http://www.iata.org/index.htm">International Air Transport
321
<a href="http://iata.org/index.htm">International Air Transport
325
323
gives current time zone rules for airports served by commercial aviation.</li>
326
324
<li>Some Microsoft Windows versions contain time zone information in
356
354
<h2>Time zone boundaries</h2>
358
<li><a href="http://www.efele.net/maps/">A map of the TZ timezones in
356
<li><a href="http://efele.net/maps/">A map of the TZ timezones in
359
357
the US</a> contains a <a
360
358
href="http://en.wikipedia.org/wiki/Shapefile">shapefile</a> of the
361
359
<code>tz</code> regions in the US.</li>
362
<li><a href="http://www.statoids.com/statoids.html">Administrative Divisions
360
<li><a href="http://statoids.com/statoids.html">Administrative Divisions
363
361
of Countries ("Statoids")</a> contains detailed lists of
364
362
<code>tz</code>-related zone subdivision data.</li>
365
363
<li><a href="http://home.tiscali.nl/~t876506/Multizones.html">Time
396
394
<li><a href="http://webexhibits.org/daylightsaving/">About Daylight
397
395
Saving Time - History, rationale, laws & dates</a>
398
396
is an overall history of <abbr>DST</abbr>.</li>
399
<li><a href="http://www.energy.ca.gov/daylightsaving.html">Saving Time,
397
<li><a href="http://energy.ca.gov/daylightsaving.html">Saving Time,
400
398
Saving Energy</a> discusses a primary justification for <abbr>DST</abbr>.</li>
401
<li><a href="http://www.seizethedaylight.com/dst/">Who Knew? A Brief
399
<li><a href="http://seizethedaylight.com/dst/">Who Knew? A Brief
402
400
History of Daylight Saving Time</a> summarizes some of the contentious
403
401
history of <abbr>DST</abbr>.</li>
404
402
<li><a href="http://toi.iriti.cnr.it/">The
420
418
note on daylight saving time in Australia</a>.
421
419
The Bureau of Meteorology publishes a list of
422
420
<a href="http://www.bom.gov.au/climate/averages/tables/dst_times.shtml">Implementation Dates of Daylight Savings Time within Australia</a>.</dd>
424
<dd>The National Metrology Institute publishes a
425
table of <a href="http://www.metrologie.at/pdf/sommerzeit.pdf"
426
hreflang="de">daylight saving time in Austria (in German)</a>.</dd>
428
422
<dd>The Royal Observatory of Belgium maintains a table of <a
429
423
href="http://www.astro.oma.be/GENERAL/INFO/nli001a.html"
437
431
<dd>The Institute for National Measurement Standards publishes current
438
432
and some older information about <a
439
433
href="http://inms-ienm.nrc-cnrc.gc.ca/time_services/daylight_saving_e.html">Time
440
Zones & Daylight Saving Time</a>.
441
<a href="http://www3.sympatico.ca/c.walton/canada_dst.html">Canadian
442
Daylight Saving Regulations</a> summarizes changes for 2007.</dd>
434
Zones & Daylight Saving Time</a>.</dd>
444
436
<dd>The Chilean Hydrographic and Oceanographic Service publishes a <a
445
437
href="http://www.horaoficial.cl/horaof.htm" hreflang="es"> history of
465
457
covers the history of local time in the Netherlands from ancient times.</dd>
466
458
<dt>New Zealand</dt>
467
459
<dd>The Department of Internal Affairs maintains a brief history <a
468
href="http://www.dia.govt.nz/diawebsite.nsf/wpg_URL/Resource-material-Information-We-Provide-About-Daylight-Saving">About
460
href="http://dia.govt.nz/diawebsite.nsf/wpg_URL/Resource-material-Information-We-Provide-About-Daylight-Saving">About
469
461
Daylight Saving</a>. The privately-maintained <a
470
href="http://www.astrologyschool.com/nztime.html">History of New Zealand
462
href="http://astrologyschool.com/nztime.html">History of New Zealand
471
463
time</a> has more details.</dd>
473
465
<dd>The Norwegian Meteorological Institute lists
500
492
discusses how to synchronize clocks of
501
493
Internet hosts.</li>
503
href="ftp://ftp.rfc-editor.org/internet-drafts/draft-ietf-dhc-timezone-option-04.txt">A
504
Timezone Option for <abbr title="Dynamic Host Configuration Protocol">DHCP</abbr></a>
495
href="ftp://ftp.rfc-editor.org/in-notes/rfc4833.txt">Timezone
496
Options for <abbr title="Dynamic Host Configuration Protocol">DHCP</abbr></a>
497
(Internet <abbr>RFC</abbr> 4833)
506
499
href="http://www.dhcp.org/">DHCP</a> option for a server to configure
507
500
a client's time zone and daylight saving settings automatically.</li>
508
501
<li><a href="http://gauss.gge.unb.ca/GMT.UT.and.the.RGO.html">A Few
519
512
<abbr title="Barycentric Dynamic Time">TDB</abbr>.
520
513
<a href="http://www.ucolick.org/~sla/leapsecs/timescales.html">Time
521
514
Scales</a> goes into more detail, particularly for historical variants.</li>
522
<li>The <a href="http://www.iau.org/"><abbr
515
<li>The <a href="http://iau.org/"><abbr
523
516
title="International Astronomical Union">IAU</abbr></a>'s <a
524
517
href="http://www.iau-sofa.rl.ac.uk/"><abbr
525
518
title="Standards Of Fundamental Astronomy">SOFA</abbr></a>
552
545
International Earth Rotation Service, the committee that decides
553
546
when leap seconds occur.</li>
555
href="http://www.mail-archive.com/leapsecs@rom.usno.navy.mil/">Leap
556
Second Discussion List</a> and <a
557
href="http://rom.usno.navy.mil/archives/leapsecs.html">archive</a> covers <a
548
href="http://six.pairlist.net/mailman/listinfo/leapsecs">Leap
549
Second Discussion List</a> covers <a
558
550
href="http://gauss.gge.unb.ca/papers.pdf/gpsworld.november99.pdf">McCarthy
559
551
and Klepczynski's proposal to discontinue leap seconds</a>,
560
552
discussed further in
561
553
<a href="http://www.cl.cam.ac.uk/~mgk25/time/metrologia-leapsecond.pdf">The
562
554
leap second: its history and possible future</a>.
563
The <a href="http://www.aas.org/policy/LeapSecondCommittee.html"><abbr
555
The <a href="http://aas.org/policy/LeapSecondCommittee.html"><abbr
564
556
title="American Astronomical Society">AAS</abbr> Leap Second
565
557
Committee</a> has solicited input on this proposal.
566
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<a href="http://www.ucolick.org/~sla/leapsecs/">The
583
575
Schema: Datatypes - dateTime</a> specifies a format inspired by
584
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<abbr>ISO</abbr> 8601 that is in common use in XML data.</li>
586
<a href="ftp://ftp.rfc-editor.org/in-notes/rfc2822.txt">Internet <abbr
587
title="Request For Comments">RFC</abbr> 2822</a> §3.3
578
<a href="ftp://ftp.rfc-editor.org/in-notes/rfc2822.txt">Internet
579
Message Format</a> (Internet <abbr>RFC</abbr> 2822) §3.3
588
580
specifies the time notation used in email and <a
589
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href="ftp://ftp.rfc-editor.org/in-notes/rfc2616.txt"><abbr>HTTP</abbr></a>
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<a href="ftp://ftp.rfc-editor.org/in-notes/rfc3339.txt">Internet
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<abbr>RFC</abbr> 3339</a> specifies an <abbr>ISO</abbr> 8601
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<a href="ftp://ftp.rfc-editor.org/in-notes/rfc3339.txt">Date and Time
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on the Internet: Timestamps</a> (Internet <abbr>RFC</abbr> 3339)
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specifies an <abbr>ISO</abbr> 8601
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profile for use in new Internet
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French translations for "Eastern European Summer Time", "<abbr
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title="Eastern European Summer Time">EEST</abbr>", and
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href="http://unicode.org/cldr/data/charts/by_type/names.zone.html">By-Type
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Chart: names.zone</a> shows these values for many locales.
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href="http://unicode.org/cldr/data/charts/by_type/names.metazone.html">By-Type
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Chart: names.metazone</a> shows these values for many locales.
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<abbr>ICU</abbr> contains a mechanism for using this data.</li>
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<li>Alphabetic time zone abbreviations should not be used as unique
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identifiers for <abbr>UTC</abbr> offsets as they are ambiguous in
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<h2>Related indexes</h2>
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<li><a href="tz-art.htm">Time and the Arts</a></li>
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<li><a href="http://dmoz.org/Reference/Time/">Open Directory -
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<li><a href="http://www.dmoz.org/Reference/Time/">Open Directory -
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Reference: Time</a></li>
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<li><a href="http://directory.google.com/Top/Reference/Time/">Google Directory
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- Reference > Time</a></li>
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<li><a href="http://dir.yahoo.com/Science/Measurements_and_Units/Time/">Yahoo!
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<li><a href="http://dir.yahoo.com/Science/Measurements_and_Units/Time">Yahoo!
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Directory > Science > Measurements and Units > Time</a></li>