ব্যাংকের চেক বই আইডেন্টিফিকেশনে ব্যবহৃত হয় -

MICR code is a code printed on cheques using MICR (Magnetic Ink Character Recognition technology).
This enables identification of the cheques and which in turns means faster processing.

An MICR code is a 9-digit code that uniquely identifies the bank and branch participating in an Electronic Clearing System (ECS).
Source: economictimes.indiatimes.com