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 29For changes that fix sensitive security-related bugs, please see the 30file SECURITY. 31 32Please submit changes against either the latest release in 33<https://www.iana.org/time-zones> or the main branch of the development 34repository. The latter is preferred. If you use Git the following 35workflow may be helpful: 36 37 * Copy the development repository. 38 39 git clone https://github.com/eggert/tz.git 40 cd tz 41 42 * Get current with the main branch. 43 44 git checkout main 45 git pull 46 47 * Switch to a new branch for the changes. Choose a different 48 branch name for each change set. 49 50 git checkout -b mybranch 51 52 * Sleuth by using 'git blame'. For example, when fixing data for 53 Africa/Sao_Tome, if the command 'git blame africa' outputs a line 54 '2951fa3b (Paul Eggert 2018-01-08 09:03:13 -0800 1068) Zone 55 Africa/Sao_Tome 0:26:56 - LMT 1884', commit 2951fa3b should 56 provide some justification for the 'Zone Africa/Sao_Tome' line. 57 58 * Edit source files. Include commentary that justifies the 59 changes by citing reliable sources. 60 61 * Debug the changes, e.g.: 62 63 make check 64 make install 65 ./zdump -v America/Los_Angeles 66 67 * For each separable change, commit it in the new branch, e.g.: 68 69 git add northamerica 70 git commit 71 72 See recent 'git log' output for the commit-message style. 73 74 * Create patch files 0001-*, 0002-*, ... 75 76 git format-patch main 77 78 * After reviewing the patch files, send the patches to tz@iana.org 79 for others to review. 80 81 git send-email main 82 83 For an archived example of such an email, see 84 <https://mm.icann.org/pipermail/tz/2018-February/026122.html>. 85 86 * Start anew by getting current with the main branch again 87 (the second step above). 88 89Please do not create issues or pull requests on GitHub, as the 90proper procedure for proposing and distributing patches is via 91email as illustrated above. 92 93----- 94 95This file is in the public domain. 96