Requirements for adding new orth file:

* we are following up to the locale name, 2 or 3 letter code
  in ISO 639 and ISO 3166-1 alpha-2 code to determine a
  filename. if it's not yet available, in advance, you
  should get it fixed in glibc or so.

* Please add a reference URL (written in English as far as
  possible) into the orth file that explains the code
  coverage for the certain language. this would helps to
  review if it has enough coverage.

* no need to add all of the codepoints for the certain
  language. good enough if it covers most frequently used
  codepoints in it.

To update existing orth files:

* Please make sure how the changes affects to the existing
  fonts and no regressions except it is expected behavior.

* Please add any reference URL in bugzilla or any
  explanation why it needs to be added/removed and also why
  current orth file doesn't work.

* Please provide a test case what fonts are supposed to be
  accepted against the change and what fonts aren't.