the code is overall the whole picture. Even in non-printed areas (its still printed as fine dots on areas that actually are "void"). You need around 4x4cm (as my experiments some years ago concluded). That code-tile is repeated over the whole area. Typically, your thumb may cover some parts, but there are other parts that are scanned and which holds the encoded things.

Even better: you can encode an ID like in qr/barcode or what ever you want or you also can encode URLs and have some backend processing the "access to the partial URL". You can have a lot information encoded. As i remember its more than with ordinary QR code at the same area. May be I have forgotten something.

Its actually the base for the "holy grail 2.0" initiative to make recycling of printed packaging better. It then doesnt even matter if you only have a peace of the packaging. It must be big enough to carry the code (that roughly 4x4 cm). The code has some ID which is looked up and then all the information neccessary to know what material it is, how to recycle it - all the important things can be looked up in the DB and then handled accordingly.

its a nice thing with own problems, but better approach as barcode/qr code.