Copyright (C) 1999-2001, International Business Machines Corporation and others. All Rights Reserved. Readme file for ICU time zone data (source/tools/gentz) Alan Liu Last updated 2 Feb 2001 RAW DATA -------- The time zone data in ICU is taken from the UNIX data files at ftp://elsie.nci.nih.gov/pub/tzdata. The other input to the process is an alias table, described below. BUILD PROCESS ------------- Two tools are used to process the data into a format suitable for ICU: tz.pl directory of raw data files + tz.alias -> tz.txt gentz tz.txt -> tz.dat (memory mappable binary file) After gentz is run, standard ICU data tools are used to incorporate tz.dat into the icudata module. The tz.pl script is run manually; everything else is automatic. In order to incorporate the raw data from that source into ICU, take the following steps. 1. Download the archive of current zone data. This should be a file named something like tzdata1999j.tar.gz. Use the URL listed above. 2. Unpack the archive into a directory, retaining the name of the archive. For example, unpack tzdata1999j.tar.gz into tzdata1999j/. Place this directory anywhere; one option is to place it within source/tools/gentz. 3. Run the perl script tz.pl, passing it the directory location as a command-line argument. On Windows system use the batch file tz.bat. Also specify one or more ourput files: .txt, .htm|.html, and .java. For ICU4C specify .txt; typically /source/data/misc/timezone.txt where icu is the ICU4C root directory. Double check that this is the correct location and file name; they change periodically. It is useful to generate an html file. After it is generated, review it for correctness. As the third argument, pass in "tz.java". This will generate a java source file that will be used to update the ICU4J data. 4. Do a standard build. The build scripts will automatically detect that a new .txt file is present and rebuild the binary data (using gentz) from that. The .txt and .htm files and typically checked into CVS, whereas the raw data files are not, since they are readily available from the URL listed above. Additional steps are required to update the ICU4J data. First you must have a current, working installation of icu4j. These instructions will assume it is in directory "/icu4j". 5. Copy the tz.java file generated in step 3 to /icu4j/tz.java. 6. Change to the /icu4j directory and compile the tz.java file, with /icu4j/classes on the classpath. 7. Run the resulting java program (again with /icu4j/classes on the classpath) and capture the output in a file named tz.tmp. 8. Open /icu4j/src/com/ibm/util/TimeZoneData.java. Delete the section that starts with the line "BEGIN GENERATED SOURCE CODE" and ends with the line "END GENERATED SOURCE CODE". Replace it with the contents of tz.tmp. If there are extraneous control-M characters or other similar problems, fix them. 9. Rebuild icu4j and make sure there are no build errors. Rerun all the tests in /icu4j/src/com/ibm/test/timezone and make sure they all pass. If all is well, check the new TimeZoneData.java into CVS. ALIAS TABLE ----------- For backward compatibility, we define several three-letter IDs that have been used since early ICU and correspond to IDs used in old JDKs. These IDs are listed in tz.alias. The tz.pl script processes this alias table and issues errors if there are problems. IDS --- All *system* zone IDs must consist only of characters in the invariant set. See utypes.h for an explanation of what this means. If an ID is encountered that contains a non-invariant character, tz.pl complains. Non-system zones may use non-invariant characters. Etc/GMT... ---------- Users may be confused by the fact that various zones with names of the form Etc/GMT+n appear to have an offset of the wrong sign. For example, Etc/GMT+8 is 8 hours *behind* GMT; that is, it corresponds to what one typically sees displayed as "GMT-8:00". The reason for this inversion is explained in the UNIX zone data file "etcetera". Briefly, this is done intentionally in order to comply with POSIX-style signedness. In ICU we reproduce the UNIX zone behavior faithfully, including this confusing aspect.