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CONTRIBUTING revision 1.3.2.2 
      1 Contributing to the tz code and data
      2 
      3 The time zone database is by no means authoritative: governments
      4 change timekeeping rules erratically and sometimes with little
      5 warning, the data entries do not cover all of civil time before
      6 1970, and undoubtedly errors remain in the code and data.  Feel
      7 free to fill gaps or fix mistakes, and please email improvements
      8 to tz (a] iana.org for use in the future.  In your email, please give
      9 reliable sources that reviewers can check.
     10 
     11 -----
     12 
     13 Developers can contribute technical changes to the source code and
     14 data as follows.
     15 
     16 To email small changes, please run a POSIX shell command like
     17 'diff -u old/europe new/europe >myfix.patch', and attach
     18 myfix.patch to the email.
     19 
     20 For more-elaborate or possibly-controversial changes,
     21 such as renaming, adding or removing zones, please read
     22 <https://www.iana.org/time-zones/repository/theory.html> or the file
     23 theory.html.  It is also good to browse the mailing list archives
     24 <https://mm.icann.org/pipermail/tz/> for examples of patches that tend
     25 to work well.  Additions to data should contain commentary citing
     26 reliable sources as justification.  Citations should use https: URLs
     27 if available.
     28 
     29 Please submit changes against either the latest release in
     30 <https://www.iana.org/time-zones> or the master branch of the development
     31 repository.  The latter is preferred.  If you use Git the following
     32 workflow 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 (a] 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 
     86 Please do not create issues or pull requests on GitHub, as the
     87 proper procedure for proposing and distributing patches is via
     88 email as illustrated above.
     89