x5b'date_format'\x5d

I think it is supposed to order the drop downs for day/month/year on http://wikipedia.ramselehof.de/wikiblame.php and possibly some output. Not sure though, and I do not see it working.

Thank you. This message is now appearing in the interface. I have opened a bug request on SourceForge for this.

 Done. Explanation received and documented.