1e27ed2014-09-04Henrik Grubbström (Grubba) Contributing to the tz code and data The time zone database is by no means authoritative: governments change timekeeping rules erratically and sometimes with little warning, the data entries do not cover all of civil time before 1970, and undoubtedly errors remain in the code and data. Feel free to fill gaps or fix mistakes, and please email improvements
8de8e92017-11-17Henrik Grubbström (Grubba) to tz@iana.org for use in the future. In your email, please give reliable sources that reviewers can check. ----- Developers can contribute technical changes to the source code and data as follows.
1e27ed2014-09-04Henrik Grubbström (Grubba)  To email small changes, please run a POSIX shell command like 'diff -u old/europe new/europe >myfix.patch', and attach myfix.patch to the email.
104d152018-12-18Henrik Grubbström (Grubba) For more-elaborate or possibly-controversial changes, such as renaming, adding or removing zones, please read <https://www.iana.org/time-zones/repository/theory.html> or the file theory.html. It is also good to browse the mailing list archives <https://mm.icann.org/pipermail/tz/> for examples of patches that tend to work well. Additions to data should contain commentary citing reliable sources as justification. Citations should use https: URLs if available.
1e27ed2014-09-04Henrik Grubbström (Grubba)  Please submit changes against either the latest release in
8de8e92017-11-17Henrik Grubbström (Grubba) <https://www.iana.org/time-zones> or the master branch of the development
07968a2018-09-05Henrik Grubbström (Grubba) repository. The latter is preferred. If you use Git the following workflow may be helpful:
1e27ed2014-09-04Henrik Grubbström (Grubba) 
5bee8d2016-11-26Henrik Grubbström (Grubba)  * Copy the development repository.
1e27ed2014-09-04Henrik Grubbström (Grubba)  git clone https://github.com/eggert/tz.git cd tz * Get current with the master branch. git checkout master git pull * Switch to a new branch for the changes. Choose a different branch name for each change set. git checkout -b mybranch
07968a2018-09-05Henrik Grubbström (Grubba)  * Sleuth by using 'git blame'. For example, when fixing data for Africa/Sao_Tome, if the command 'git blame africa' outputs a line '2951fa3b (Paul Eggert 2018-01-08 09:03:13 -0800 1068) Zone Africa/Sao_Tome 0:26:56 - LMT 1884', commit 2951fa3b should provide some justification for the 'Zone Africa/Sao_Tome' line.
1e27ed2014-09-04Henrik Grubbström (Grubba)  * Edit source files. Include commentary that justifies the changes by citing reliable sources. * Debug the changes, e.g.: make check make install ./zdump -v America/Los_Angeles * For each separable change, commit it in the new branch, e.g.: git add northamerica git commit See recent 'git log' output for the commit-message style. * Create patch files 0001-*, 0002-*, ... git format-patch master * After reviewing the patch files, send the patches to tz@iana.org for others to review. git send-email master
07968a2018-09-05Henrik Grubbström (Grubba)  For an archived example of such an email, see <https://mm.icann.org/pipermail/tz/2018-February/026122.html>.
1e27ed2014-09-04Henrik Grubbström (Grubba)  * Start anew by getting current with the master branch again (the second step above). Please do not create issues or pull requests on GitHub, as the proper procedure for proposing and distributing patches is via email as illustrated above.
ac5f542016-02-07Henrik Grubbström (Grubba)  ----- This file is in the public domain.