An excerpt from an email from Marc:

but your kaywa reader is only for Qr Code?
Don't you like datamtrix technology?

As this is a recurrent question, I want to answer it once and for all;)

The Kaywa Reader reads both QR Codes and Datamatrix;)
And you can also create both: here and there.

We love open, well defined, certified and thought through standards* and Datamatrix as well as QR Code fall into this category, but QR Code is definitely the better code for all things mobile and especially mobile tagging. There are several reasons:

1. The QR Code is "iconic", whereas Datamatrix is not very attractive (it's has no form, it's a mess).
2. Especially Women** and the Creative*** adore QR Codes (nonetheless the European Central Bank and the business executive school IMD also love it)
3. People on the web have already "voted" for QR Code
4. Japan has pioneered QR Codes on mobile phones since 2003 and all global brands have already used it (from Nike to McDonalds, from Zurich Assurances to BMW).
5. The incredible fast way of adopting QR Codes in Japan and Taiwan is a very promising sign
6. Japanses pop culture is to my sons generation what american pop culture was for me. Youth today is therefore continously in contact with QR Codes. Just buy your son a Naruto plastic toy and you can't miss it.
7. The japanese example is right - offline and online codes - especially in a time where consumers fear to spend a lot of money by accessing the mobile internet (even if this is true for Datamatrix, the QR Code set the good example - and so far most european Datamatrix initiatives are not very keen to adopt the "offline+online" model.
8. Here in Switzerland we have Datamatrix on our bills and it is therefore
a) confusing (which code is to read for mobile phones and which one is only for internal use; you would have to add a marker to the code to differentiate them)
b) some associations ("I have to pay this") could be harmful

* Would there be a web without HTML, and think why SMS became such a global success?
** The publishing company Axel Springer did some study on this
*** Just watch the Pet Shop Boys video, Spex or Zadig&Voltaire