Lots of business letters use this as stamps. and the “Die Bahn” use that on the online tickets. so the conductors use this for check if the ticket is valid.

and by the way, greetz from berlin!

Thanks for the information, there isn’t much information about RQ-codes on this side of the world yet, is that why you did not use the word?

(Incase I referenced this post here: http://3spots.blogspot.com/2006/03/rq-code-what-are-these-images-we-see.html)