227 lines
10 KiB
HTML
227 lines
10 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
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<HTML>
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<HEAD>
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<TITLE>Sources for Time Zone and Daylight Saving Time Data</TITLE>
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<LINK REL="schema.DC" HREF="http://purl.org/DC/elements/1.1/">
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<META NAME="DC.Creator" CONTENT="Paul Eggert">
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<META NAME="DC.Contributor" CONTENT="Arthur David Olson">
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<META NAME="DC.Date" CONTENT="2000/10/03">
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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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<META NAME="Keywords"
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CONTENT="database,daylight saving,DST,time zone,timezone,tz,zoneinfo">
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</HEAD>
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<BODY>
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<H1>Sources for Time Zone and Daylight Saving Time Data</H1>
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<ADDRESS>
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@(#)tz-link.htm 7.28
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</ADDRESS>
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<P>
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Please send corrections to this web page to the
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<A HREF="mailto:tz@elsie.nci.nih.gov">time zone mailing list</A>.
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<P>
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<H2>The <samp>tz</samp> database</H2><P>
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The public-domain time zone database contains code and data
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that represent the history of local time
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for many representative locations around the globe.
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It is updated periodically to reflect changes made by political bodies
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to UTC offsets and daylight-saving rules.
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This database (often called <samp>tz</samp> or <samp>zoneinfo</samp>)
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is used by several implementations,
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including BSD, DJGPP, GNU/Linux, HP-UX, IRIX, Solaris, and UnixWare.
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In the <samp>tz</samp> database's
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<A HREF="ftp://elsie.nci.nih.gov/pub/">FTP distribution</A>,
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the code is in the file <samp>tzcode<var>C</var>.tar.gz</samp>,
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where <samp><var>C</var></samp> is the code's version;
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similarly, the data are in <samp>tzdata<var>D</var>.tar.gz</samp>,
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where <samp><var>D</var></samp> is the data's version.
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The code lets you compile the text data into time zone files, one for
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each location. It also lets you read a compiled time zone file and
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interpret time stamps for that location.
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<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="mailto:tz-request@elsie.nci.nih.gov">subscribe</A> to the
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mailing list, or retrieve the <A
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HREF="ftp://elsie.nci.nih.gov/pub/tzarchive.gz">archive of old
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messages</A> (in <A HREF="http://www.gzip.org/">gzip</A> compressed
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format).
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<P>
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The Web has several other sources for time zone and daylight saving time data.
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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 <samp>tz</samp> database</H2>
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<UL>
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<LI><A HREF="http://www.bsdi.com/date/">Date and Time Gateway</A> is a
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text-based point-and-click interface to tables of current time
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throughout the world.
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<LI><A HREF="http://sandbox.xerox.com/stewart/tzconvert.cgi">CGI/1.0
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URL Timezone Converter</A> is a similar interface, with source code
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written in <A HREF="http://www.perl.org/">Perl</A>, using what Paul
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Stewart calls the "20-line hack no one will let me forget".
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<LI><A HREF="http://www.hilink.com.au/times/">Local Times Around the World</A>
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is a fancier web interface.
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<LI><A HREF="http://timezoneconverter.com/">Time Zone Converter</A>
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is an even fancier interface.
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<LI><A HREF="http://www.tick2tock.com/cgi-bin/TZConverter">Tick2Tock
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time zone converter</A> is a multilingual interface.
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<LI><A HREF="http://www.holidayfestival.com/">The Worldwide Holiday
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& Festival Site</A> lists DST-related clock changes along with holidays.
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<LI><A HREF="http://www.timeanddate.com/worldclock/">The World Clock</A>
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is a web interface to a time zone database derived from
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<samp>tz</samp>'s.
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</UL>
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<H2>Other time zone file readers</H2>
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<UL>
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<LI>The <A HREF="http://www.gnu.org/software/libc/">GNU C Library</A>
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has an independent, thread-safe implementation of
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a time zone file reader that is compatible with <samp>tz</samp>.
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This library is freely available under the
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<A HREF="http://www.gnu.org/copyleft/lesser.html">
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GNU Lesser General Public License (LGPL)</A>,
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and is widely used in GNU/Linux systems.
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<LI><A HREF="http://www.bmsi.com/java/#TZ">ZoneInfo.java</A>
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is a time zone file reader written in Java.
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It is freely available under the GNU LGPL.
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</UL>
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<H2>Other <SAMP>tz</SAMP>-based time zone conversion software</H2>
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<UL>
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<LI><A
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HREF="http://www1.tip.nl/~t876506/AboutTimeZonesHC.html">HyperCard
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time zones calculator</A> is a HyperCard stack.
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<LI><A
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HREF="http://timezone50.homepage.com/">Time Zone Converter</A> is a
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Microsoft Windows 95/98/NT4 program.
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</UL>
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<H2>Other time zone databases</H2>
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<UL>
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<LI><A HREF="http://www.astro.ch/atlas/">Astrodienst Online -
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Atlas & Timezone Database</A> is Astrodienst's Web version of Shanks's
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excellent time zone history atlases published in both <A
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HREF="http://astrocom.com/software/ACS_PC_Atlas.htm">computer</A> and <A
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HREF="http://astrocom.com/books/xrefa.htm#SHANKS">book</A> form by <A
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HREF="http://astrocom.com/">Astro Communications Services</A>.
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<LI><A HREF="http://worldtime.com/">WORLDTIME: interactive atlas,
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time info, public holidays</A>
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contains information on local time, sunrise and sunset,
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and public holidays in several hundred cities around the world.
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<LI><A HREF="http://tycho.usno.navy.mil/tzones.html">World Time Zones</A>
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contains data from the Time Service Department of the US Naval Observatory
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(USNO), used as the source
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for the <samp>usno*</samp> files in the <samp>tz</samp> distribution.
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<LI>The USNO Astronomical Applications Department publishes answers to
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<A HREF="http://aa.usno.navy.mil/AA/faq/">Frequently Asked Questions</A>
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about time zones and daylight saving time.
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<LI>The <A HREF="http://www.iata.org/">International
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Air Transport Association</A>
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publishes the IATA Standard Schedules Information Manual (SSIM),
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which gives current time zone rules for
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all the airports served by commercial aviation.
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</UL>
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<H2>Maps</H2>
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<UL>
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<LI>The United States Central Intelligence Agency publishes a <A
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HREF="http://www.odci.gov/cia/publications/factbook/reference/Low%20res%20PDF/low802700.pdf">time
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zone map</A>; the
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<A HREF="http://www.lib.utexas.edu/Libs/PCL/Map_collection/world_maps.html">
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Perry-Castañeda Library Map Collection</A>
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of the University of Texas at Austin has on-line copies of
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recent editions.
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The pictorial quality is good,
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but the maps do not indicate summer time,
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and parts of the data are a few years out of date.
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<LI><A HREF="http://worldtimezone.com/">World timezones map with
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current time</A>
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has several fancy time zone maps; it covers Russia particularly well.
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The maps' pictorial quality is not quite as good as the CIA's
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and (as usual with maps) the maps are not quite up to date.
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<LI><A HREF="http://www.worldtimeserver.com/">World Time Server</A>
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has a separate little outline map for each region of each country that
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currently observes a different time.
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</UL>
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<H2>Daylight saving time concepts and history</H2>
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<UL>
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<LI><A HREF="http://webexhibits.com/daylightsaving/">About Daylight
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Saving Time - History, rationale, laws and dates</A>
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is a good overall history of DST.
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<LI><A HREF="http://www.cstv.to.cnr.it/toi/uk/toi.html">The
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Time of Internet</A>
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contains good descriptions of Time Zones and daylight saving time,
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with diagrams.
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The time zone map is out of date, however.
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<LI>A few countries have well-documented histories of legal time.
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<DL>
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<DT>Australia
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<DD>The Community Relations Division of the NSW Attorney General's
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Department maintains a history of <A
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HREF="http://www.lawlink.nsw.gov.au/crd.nsf/pages/time2">daylight
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saving in New South Wales</A>.
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<DT>Brazil
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<DD>The Time Service Department of the National Observatory
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records <A HREF="http://pcdsh01.on.br/DecHV.html"
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HREFLANG="pt-BR">Brazil's daylight saving time decrees (in
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Portuguese)</A>.
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<DT>Germany
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<DD>The National Institute for Science and Technology maintains <A
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HREF="http://www.ptb.de/english/org/4/43/432/lega.htm">a history of
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German legal time</A>.
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<DT>Israel
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<DD>The Ministry of Interior periodically issues <A
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HREF="ftp://ftp.huji.ac.il/pub/tz/announcements"
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HREFLANG="he">announcements (in Hebrew)</A>.
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<DT>United Kingdom
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<DD><A
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HREF="http://student.cusu.cam.ac.uk/~jsm28/british-time/">History of
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legal time in Britain</A> is an excellent discussion for the country
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with perhaps the best-documented history of clock adjustments.
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</DL>
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</UL>
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<H2>Precision timekeeping</H2>
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<UL>
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<LI><A HREF="http://www.eecis.udel.edu/~ntp/">Time Server</A> discusses
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the Network Time Protocol (NTP), used to synchronize clocks of Internet hosts.
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<LI><A HREF="http://ecco.bsee.swin.edu.au/chronos/GMT-explained.html">A
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Few Facts Concerning GMT, UT, and the RGO</A>
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answers questions like "What is the difference between GMT and UTC?"
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<LI><A
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HREF="http://sadira.gb.nrao.edu/~rfisher/Ephemerides/times.html">Astronomical
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Times</A> explains more abstruse astronomical time scales like TT, TCG,
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and TDB.
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<LI><A HREF="http://www.jpl.nasa.gov/basics/bsf2-3.htm">Earth
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and Its Reference Systems</A>
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briefly explains interplanetary space flight timekeeping.
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<LI><A HREF="http://hpiers.obspm.fr/webiers/results/bul/README.html">Bulletins
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of IERS</A> contains official publications of the
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International Earth Rotation Service, the committee that decides
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when leap seconds occur.
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<LI>The <A
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HREF="http://clockdev.usno.navy.mil/archives/leapsecs.html">Leap
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Second Discussion List</A> covers <A
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HREF="http://clockdev.usno.navy.mil/cgi-bin/wa.exe?A3=ind0007&L=leapsecs&P=26737&E=2&B=------_=_NextPart_000_01BFEAA4.2B254664&N=GPS-Nov99_Innov.pdf&T=application/octet-stream">McCarthy
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and Klepczynski's proposal to remove leap seconds</A>, currently
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being studied by a <A
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HREF="http://www.intec.rug.ac.be/Research/Projects/ursi/Commissions.html">URSI
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Commission J</A> working group, and the <A HREF="http://www.iau.org/">IAU</A>
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has <A
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HREF="http://clockdev.usno.navy.mil/cgi-bin/wa.exe?A2=ind0009&L=leapsecs&F=lf&S=&P=2658">plans</A>
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to report on this proposal by 2003.
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</UL>
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<H2>Time notation</H2>
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<UL>
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<LI>
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<A HREF="http://www.cl.cam.ac.uk/~mgk25/iso-time.html">A Summary of
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the International Standard Date and Time Notation</A> is a good
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summary of <A HREF="http://www.iso.ch/markete/moreend.htm">ISO
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8601</A>.
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</UL>
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<H2>Related indexes</H2>
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<UL>
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<LI><A HREF="http://dmoz.org/Reference/Time/">Open Directory -
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Reference: Time</A>
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<LI><A HREF="tz-art.htm">Time and the Arts</A>
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<LI><A HREF="http://dir.yahoo.com/Science/Measurements_and_Units/Time/Time_Zones/">Yahoo! - Science:Measurements and Units:Time:Time Zones</A>
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</UL>
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</BODY>
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</HTML>
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