Then it relies on the fixed grid [0] and font to do a "poor man's OCR" [1] when decoding.
[0] http://git.io/vIWll [1] http://git.io/vIWln [2] https://twitter.com/Lukasaoz/status/607632001210925056
The interesting thing about the poor man's OCR is that it works way better than out of the box OCR tools. They're all built around handling arbitrary, often quite noisy input, so their handling of 1s and ls in this data is often not great.
Doing the cheap OCR works really well because we can overfit our data: we know the font, we know the grid, and we know the orientation, so our problem is way simpler than generic OCR.