DougHW/php.mo — pull request #1 by GautamGupta (2012-05-17 20:30:57+00:00)
Title: Don't export untranslated strings in mo files.

As their exported counterpart is stored as nothing, the strings are not displayed in the software. So it's a good idea to leave out the untranslated strings from being exported into the mo files imo. :)