Developed in 1970 by Identicon Corporation and the Computer Identics Corporation in the late 1960s, Code 2 of 5 – also called Industry 2 of 5 – is part of the larger code family known as “2 of 5 interleaved.” Unlike newer barcode formats, Code 2 of 5 encodes all data within bars, using the spaces only to separate the encoded bar data. As a result, this code is inefficient compared to more modern codes which use both bars and blank spaces as part of their encoding symbology. The barcode takes its name from the fact that 2 of every 5 five bars are wide and 3 are narrow.
Code 2 of 5 encodes numeric data only, and most barcode readers will generate an error if any non-numeric characters are included. Code 2 of 5 is also a self-checking barcode, which means no checksum is required. It is possible, however, to include an optional modulo checksum if desired.