https://en.m.wikipedia.org/wiki/Machine_Identification_Code https://en.m.wikipedia.org/wiki/Machine_Identification_Code but idk about how many printers do this

https://en.m.wikipedia.org/wiki/Machine_Identification_Code https://en.m.wikipedia.org/wiki/Machine_Identification_Code but idk about how many printers do this or whether similar techniques are used for black+white printers (i.e. gray-scale modulation)