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 changes, please read the theory.html file and browse 21the mailing list archives <https://mm.icann.org/pipermail/tz/> for 22examples of patches that tend to work well. Additions to 23data should contain commentary citing reliable sources as 24justification. Citations should use https: URLs if available. 25 26Please submit changes against either the latest release in 27<https://www.iana.org/time-zones> or the master branch of the development 28repository. The latter is preferred. If you use Git the following 29workflow may be helpful: 30 31 * Copy the development repository. 32 33 git clone https://github.com/eggert/tz.git 34 cd tz 35 36 * Get current with the master branch. 37 38 git checkout master 39 git pull 40 41 * Switch to a new branch for the changes. Choose a different 42 branch name for each change set. 43 44 git checkout -b mybranch 45 46 * Sleuth by using 'git blame'. For example, when fixing data for 47 Africa/Sao_Tome, if the command 'git blame africa' outputs a line 48 '2951fa3b (Paul Eggert 2018-01-08 09:03:13 -0800 1068) Zone 49 Africa/Sao_Tome 0:26:56 - LMT 1884', commit 2951fa3b should 50 provide some justification for the 'Zone Africa/Sao_Tome' line. 51 52 * Edit source files. Include commentary that justifies the 53 changes by citing reliable sources. 54 55 * Debug the changes, e.g.: 56 57 make check 58 make install 59 ./zdump -v America/Los_Angeles 60 61 * For each separable change, commit it in the new branch, e.g.: 62 63 git add northamerica 64 git commit 65 66 See recent 'git log' output for the commit-message style. 67 68 * Create patch files 0001-*, 0002-*, ... 69 70 git format-patch master 71 72 * After reviewing the patch files, send the patches to tz@iana.org 73 for others to review. 74 75 git send-email master 76 77 For an archived example of such an email, see 78 <https://mm.icann.org/pipermail/tz/2018-February/026122.html>. 79 80 * Start anew by getting current with the master branch again 81 (the second step above). 82 83Please do not create issues or pull requests on GitHub, as the 84proper procedure for proposing and distributing patches is via 85email as illustrated above. 86 87----- 88 89This file is in the public domain. 90