Apparently this has been going on for years, but it’s only now in this PCWorld article that this is becoming common knowledge.
Peter Crean, a senior research fellow at Xerox, says his company’s laser printers, copiers and multifunction workstations, such as its WorkCentre Pro series, put the “serial number of each machine coded in little yellow dots” in every printout. The millimeter-sized dots appear about every inch on a page, nestled within the printed words and margins.
“It’s a trail back to you, like a license plate,” Crean says.
The dots’ minuscule size, covering less than one-thousandth of the page, along with their color combination of yellow on white, makes them invisible to the naked eye, Crean says. One way to determine if your color laser is applying this tracking process is to shine a blue LED light–say, from a keychain laser flashlight–on your page and use a magnifier.
I have a nice Xerox Phaser 860DP here at the office, and I’m going to see if I can find a blue LED to see if I can find the damn serial number. It just makes me wonder what else these machines are hiding from me.