1Contributing to the tz code and data 2 3The time zone database is by no means authoritative: governments 4change timekeeping rules erratically and sometimes with little 5warning, the data entries do not cover all of civil time before 61970, and undoubtedly errors remain in the code and data. Feel 7free to fill gaps or fix mistakes, and please email improvements 8to tz@iana.org for use in the future. In your email, please give 9reliable sources that reviewers can check. 10 11----- 12 13Developers can contribute technical changes to the source code and 14data as follows. 15 16To email small changes, please run a POSIX shell command like 17'diff -u old/europe new/europe >myfix.patch', and attach 18myfix.patch to the email. 19 20For more-elaborate or possibly-controversial changes, 21such as renaming, adding or removing zones, please read 22<https://www.iana.org/time-zones/repository/theory.html> or the file 23theory.html. It is also good to browse the mailing list archives 24<https://mm.icann.org/pipermail/tz/> for examples of patches that tend 25to work well. Additions to data should contain commentary citing 26reliable sources as justification. Citations should use https: URLs 27if available. 28 29Please submit changes against either the latest release in 30<https://www.iana.org/time-zones> or the master branch of the development 31repository. The latter is preferred. If you use Git the following 32workflow may be helpful: 33 34 * Copy the development repository. 35 36 git clone https://github.com/eggert/tz.git 37 cd tz 38 39 * Get current with the master branch. 40 41 git checkout master 42 git pull 43 44 * Switch to a new branch for the changes. Choose a different 45 branch name for each change set. 46 47 git checkout -b mybranch 48 49 * Sleuth by using 'git blame'. For example, when fixing data for 50 Africa/Sao_Tome, if the command 'git blame africa' outputs a line 51 '2951fa3b (Paul Eggert 2018-01-08 09:03:13 -0800 1068) Zone 52 Africa/Sao_Tome 0:26:56 - LMT 1884', commit 2951fa3b should 53 provide some justification for the 'Zone Africa/Sao_Tome' line. 54 55 * Edit source files. Include commentary that justifies the 56 changes by citing reliable sources. 57 58 * Debug the changes, e.g.: 59 60 make check 61 make install 62 ./zdump -v America/Los_Angeles 63 64 * For each separable change, commit it in the new branch, e.g.: 65 66 git add northamerica 67 git commit 68 69 See recent 'git log' output for the commit-message style. 70 71 * Create patch files 0001-*, 0002-*, ... 72 73 git format-patch master 74 75 * After reviewing the patch files, send the patches to tz@iana.org 76 for others to review. 77 78 git send-email master 79 80 For an archived example of such an email, see 81 <https://mm.icann.org/pipermail/tz/2018-February/026122.html>. 82 83 * Start anew by getting current with the master branch again 84 (the second step above). 85 86Please do not create issues or pull requests on GitHub, as the 87proper procedure for proposing and distributing patches is via 88email as illustrated above. 89 90----- 91 92This file is in the public domain. 93