http://story.news.yahoo.com/news?tmp...pcworld/118664

This is a very interesting article that explains how some printer companies secretly encode information into each page printed. In order for each printout to be traced to the exact printer

According to experts, several printer companies quietly encode the serial number and the manufacturing code of their color laser printers and color copiers on every document those machines produce. Governments, including the United States, already use the hidden markings to track counterfeiters.
Very interesting...