The bottom line on all checks used in the U.S. and Canada (and many other countries worldwide) must be printed using a font called MICR (short for Magnetic Ink Character Recognition). MICR is pronounced My-ker or Mi-Ker. The bottom line on a check must always be printed in the MICR typeface using a special magnetic ink.
The MICR encoding line on a check lets the check information to be automatically read by very inexpensive machines. This is the only way that huge numbers of checks can be processed each day.
Printing MICR is relatively difficult. The MICR line needs to be printed accurate to better than 1 part in 1,000! Your magnetic toner must stay on the paper under adverse conditions and have a specific signal strength. The U.S. Check 21 Act specifies the requirements for MICR printing in the U.S. The Canadian CPA006 law specifies the Canadian requirements.
The American National Standards Institute (ANSI) has a committee that developed the MICR printing standards. The ANSI committee has mandated precise requirements for MICR fonts, toner signal strength, MICR registration, toner adhesion, and for paper grain and moisture content.
There are two published standards for MICR: the first covers printing specifications for MICR (ABA 092200) and the second covers printing placement and locations (ABA 092700). These standards that can be ordered from the American Bankers Association (ABA) in Washington, D.C.
The MICR typeface has only 14 characters in it: the numbers 0-9, and four special symbols- Transit, Amount, On-Us, and Dash. The four last characters do not exist in ASCII or on your keyboard. Since MICR has only numbers and special characters, you can not print an entire check using just this font!