<P> Duplicating this was thought to be difficult, but a criminal gang was able to reproduce it quickly . They used a cheap hot - stamping process to lay down a metal strip on the surface of the paper, then printed a pattern of solid bars over it using white ink to leave the expected metal pattern visible . At their trial, they were found to have forged tens of millions of pounds' worth of notes over a period of years . </P> <P> Because of the speed with which they can be read by computer systems, magnetic ink character recognition is used extensively in banking, primarily for personal checks . The ink used in magnetic ink character recognition (MICR) technology is also used to greatly reduce errors in automated (or computerized) reading . </P> <P> Some people believe that the magnetic ink was intended as a fraud prevention concept, yet the original intent was to have a non-optical technology so that writing on the cheque, like signatures, would not interfere with reading . The main magnetic fonts (E13 - B and CMC7) are downloadable for a small fee and in addition magnetic toner is available for many printers . Some higher resolution toners have sufficient magnetic properties for magnetic reading to be successful without special toner . </P> <P> Serial numbers help make legitimate documents easier to track and audit . To help detect forgeries serial numbers will normally have a Check digit to verify the serial number . </P>

Which is an example of printing embedded in paper