Comment by mrb

I remember a HN thread years ago on these yellow dots watermarks, where an employee at a printer manufacturer said there was no indication this was ever used by law enforcement to track who printed what because, for one, the team who implemented the watermarking never documented or taught anyone how to decode these watermarks.

Well, here we are today with this NSA story.

I think it's possible that US-based printer manufacturers implemented watermarking on special request from the NSA. That would also explain why the printer manufacturer employees never needed to teach anyone how to decode them. It wasn't their specs in the first place.