xref: /freebsd/contrib/tzdata/README (revision dd41de95a84d979615a2ef11df6850622bf6184e)
1README for the tz distribution
2
3"Where do I set the hands of the clock?" -- Les Tremayne as The King
4"Oh that--you can set them any place you want." -- Frank Baxter as The Scientist
5					(from the Bell System film "About Time")
6
7The Time Zone Database (called tz, tzdb or zoneinfo) contains code and
8data that represent the history of local time for many representative
9locations around the globe.  It is updated periodically to reflect
10changes made by political bodies to time zone boundaries, UTC offsets,
11and daylight-saving rules.
12
13See <https://www.iana.org/time-zones/repository/tz-link.html> or the
14file tz-link.html for how to acquire the code and data.  Once acquired,
15read the comments in the file 'Makefile' and make any changes needed
16to make things right for your system, especially if you are using some
17platform other than GNU/Linux.  Then run the following commands,
18substituting your desired installation directory for "$HOME/tzdir":
19
20	make TOPDIR=$HOME/tzdir install
21	$HOME/tzdir/usr/bin/zdump -v America/Los_Angeles
22
23See the file tz-how-to.html for examples of how to read the data files.
24
25This database of historical local time information has several goals:
26
27 * Provide a compendium of data about the history of civil time that
28   is useful even if not 100% accurate.
29
30 * Give an idea of the variety of local time rules that have existed
31   in the past and thus may be expected in the future.
32
33 * Test the generality of the local time rule description system.
34
35The information in the time zone data files is by no means authoritative;
36fixes and enhancements are welcome.  Please see the file CONTRIBUTING
37for details.
38
39Thanks to these Time Zone Caballeros who've made major contributions to the
40time conversion package: Keith Bostic; Bob Devine; Paul Eggert; Robert Elz;
41Guy Harris; Mark Horton; John Mackin; and Bradley White.  Thanks also to
42Michael Bloom, Art Neilson, Stephen Prince, John Sovereign, and Frank Wales
43for testing work, and to Gwillim Law for checking local mean time data.
44Thanks in particular to Arthur David Olson, the project's founder and first
45maintainer, to whom the time zone community owes the greatest debt of all.
46None of them are responsible for remaining errors.
47
48-----
49
50This file is in the public domain, so clarified as of 2009-05-17 by
51Arthur David Olson.  The other files in this distribution are either
52public domain or BSD licensed; see the file LICENSE for details.
53