Magnetic ink

Magnetic ink character recognition code (MICR Code) is a character-recognition technology used mainly by the banking industry to ease the processing and clearance of cheques and other documents. The MICR encoding, called the MICR line, is at the bottom of cheques and other vouchers and typically includes the document-type indicator, bank code, bank account number, cheque number, cheque amount, and a control indicator. The technology allows MICR readers to scan and read the information directly into a data-collection device. Unlike barcodes and similar technologies, MICR characters can be read easily by humans. The MICR E-13B font has been adopted as the international standard in ISO 1004:1995, but the CMC-7 font is widely used in Europe, Brazil and Mexico.

There are two major MICR fonts in use: E-13B and CMC-7. E-13B has a 14 character set, while CMC-7 has 15—the 10 numeric characters, plus control characters.

The MICR E-13B font is the standard in Australia, Canada, the United Kingdom, the United States, and other countries. Besides decimal digits, it also contains the following symbols: ⑆ (transit: used to delimit a bank branch routing transit number), ⑇ (amount: used to delimit a transaction amount), ⑈ (on-us: used to delimit a customer account number), and ⑉ (dash: used to delimit parts of numbers—e.g., routing numbers or account numbers).

Major European countries, including France and Italy, and others like Brazil and Mexico use the CMC-7 font, developed by Groupe Bull in 1957.

MICR characters are printed on documents in either of the MICR fonts. The ink used in the printing is a magnetic ink or toner, usually containing iron oxide. The MICR text is passed before a MICR reader. The ink in the plane of the paper is first magnetized. Then the characters are passed over a MICR read head, a device similar to the playback head of a tape recorder. As each character passes over the head it produces a unique waveform that can be easily identified by the system.

The use of MICR allows the characters to be read reliably even if they have been overprinted or obscured by other marks, such as cancellation stamps and signature. The error rate for the magnetic scanning of a typical cheque is smaller than with optical character recognition systems. For well printed MICR documents, the "can't read" rate is usually less than 1% while the substitution rate (misread rate) is in the order of 1 per 100,000 characters.

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