Check in the pristine copy of ICU 4.6...

icu46/source/tools/tzcode/readme.txt

+**********************************************************************
+* Copyright (c) 2003-2007, 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 tzcode2006h.tar.gz
+   with localtime.c  patches from tzcode2006i.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:  http://www.icu-project.org/
+Olson:  ftp://elsie.nci.nih.gov/pub/
+
+----------------------------------------------------------------------
+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://elsie.nci.nih.gov/pub/
+
+  classictzcode.tar.gz    65 KB        12/10/1994    12:00:00 AM
+  classictzdata.tar.gz    67 KB        12/10/1994    12:00:00 AM
+  e5+57.tar.gz            2909 KB      3/22/1993     12:00:00 AM
+  iso8601.ps.gz           16 KB        7/27/1996     12:00:00 AM
+  leastsq.xls             49 KB        4/24/1997     12:00:00 AM
+  ltroff.tar.gz           36 KB        7/16/1993     12:00:00 AM
+  pi.shar.gz              4 KB         3/9/1994      12:00:00 AM
+  tzarchive.gz            3412 KB      8/18/2003     4:00:00 AM
+  tzcode2003a.tar.gz      98 KB        3/24/2003     2:32:00 PM
+  tzdata2003a.tar.gz      132 KB       3/24/2003     2:32:00 PM
+
+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://elsie.nci.nih.gov/pub/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 zoneinfo.txt (from its location at
+   {path_to}/icu/source/data/misc/zoneinfo.txt) into SVN.
+