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* Copyright (C) 2016 and later: Unicode, Inc. and others.
* License & terms of use: http://www.unicode.org/copyright.html
**********************************************************************
* Copyright (c) 2003-2014, International Business Machines
* Corporation and others. All Rights Reserved.
**********************************************************************
* Author: Alan Liu
* Created: August 18 2003
* Since: ICU 2.8
**********************************************************************
Note: this directory currently contains tzcode as of tzcode2014b.tar.gz
with localtime.c patches from tzcode2014b.tar.gz
----------------------------------------------------------------------
OVERVIEW
This file describes the tools in icu/source/tools/tzcode
The purpose of these tools is to process the zoneinfo or "Olson" time
zone database into a form usable by ICU4C (release 2.8 and later).
Unlike earlier releases, ICU4C 2.8 supports historical time zone
behavior, as well as the full set of Olson compatibility IDs.
References:
ICU4C: https://icu.unicode.org/
Olson: ftp://ftp.iana.org/tz/releases/
----------------------------------------------------------------------
ICU4C vs. ICU4J
For ICU releases >= 2.8, both ICU4C and ICU4J implement full
historical time zones, based on Olson data. The implementations in C
and Java are somewhat different. The C implementation is a
self-contained implementation, whereas ICU4J uses the underlying JDK
1.3 or 1.4 time zone implementation.
Older versions of ICU (C and Java <= 2.6) implement a "present day
snapshot". This only reflects current time zone behavior, without
historical variation. Furthermore, it lacks the full set of Olson
compatibility IDs.
----------------------------------------------------------------------
BACKGROUND
The zoneinfo or "Olson" time zone package is used by various systems
to describe the behavior of time zones. The package consists of
several parts. E.g.:
Index of ftp://ftp.iana.org/tz/releases/
tzcode2014b.tar.gz 172 KB 3/25/2014 05:11:00 AM
tzdata2014b.tar.gz 216 KB 3/25/2014 05:11:00 AM
ICU only uses the tzdataYYYYV.tar.gz files,
where YYYY is the year and V is the version letter ('a'...'z').
This directory has partial contents of tzcode checked into ICU
----------------------------------------------------------------------
HOWTO
0. Note, these instructions will only work on POSIX type systems.
1. Obtain the current versions of tzdataYYYYV.tar.gz (aka `tzdata') from
the FTP site given above. Either manually download or use wget:
$ cd {path_to}/icu/source/tools/tzcode
$ wget "ftp://ftp.iana.org/tz/releases/tzdata*.tar.gz"
2. Copy only one tzdata*.tar.gz file into the icu/source/tools/tzcode/
directory (this directory).
*** Make sure you only have ONE FILE named tzdata*.tar.gz in the
directory.
3. Build ICU normally. You will see a notice "updating zoneinfo.txt..."
### Following instructions for ICU maintainers only ###
4. Obtain the current version of tzcodeYYYY.tar.gz from the FTP site to
this directory.
5. Run make target "check-dump". This target extract makes the original
tzcode and compile the original tzdata with icu supplemental data
(icuzones). Then it makes zdump / icuzdump and dump all time
transitions for all ICU timezone to files under zdumpout / icuzdumpout
directory. When they produce different results, the target returns
the error.
6. Don't forget to check in the new zoneinfo64.txt (from its location at
{path_to}/icu/source/data/misc/zoneinfo64.txt) into SVN.
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