Codabar

Codabar is a linear barcode symbology introduced by Pitney Bowes in 1972. It is sometimes referred to as NW-7 and is one of the older barcode formats still in use in certain legacy systems. Codabar is designed for simple, low-density data and can be printed with modest equipment.

The symbol encodes digits 0 through 9 and six symbols: - $ : / . +. Each character is represented by a pattern of four bars and three spaces, using two widths: narrow and wide. Start and stop characters are required to mark the beginning and end of the data; these are chosen from A, B, C, or D and frame the encoded information. The start/stop characters help scanners detect the barcode boundaries.

Codabar is relatively forgiving of printing imperfections and can be read by many inexpensive scanners. However, it offers lower data density than more modern symbologies and lacks built-in error detection or checksum schemes. Its character set is limited, and there is no standardized global checksum, which can limit interoperability across different systems and manufacturers.

Common applications have historically included libraries, where Codabar was used to label items, and blood banks or other document-tracking contexts where simple identifiers were sufficient. Today, Code 39 or Code 128 often replace Codabar in new systems due to higher density and broader character support, but Codabar persists in legacy workflows and geographies where it remains operational. Some references use NW-7 as a synonym for Codabar, with Start/Stop characters A–D being interchangeable in practice.

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