I think it’s about printers being required by law to (covertly) watermark copies as such, and make it somewhat traceable. This is supposedly to prevent duplication of protected works (books?) but also to prevent someone just using it to print money (badly, probably).
To my knowledge all major brands incorporate something like this.










This is the of the weirder interview series I’ve ever come across, and fittingly I get introduced with the correct guest. Well done. Appreciate the introduction!