Codabar

Codabar is a discrete, self-checking symbology developed in 1972, still used today in U.S. blood banks, photo labs, and FedEx airbills.

Codabar was developed in 1972 by Pitney Bowes, Inc. It is a discrete, self-checking symbology that can encode 16 different characters, plus 4 additional start/stop characters. This symbology is used by U.S. blood banks, photo labs, and on FedEx airbills.

Since Codabar is self-checking, there is no established checksum digit. Should a specific application need a checksum digit for additional security, it is up to the implementer to define and handle it. However, keep in mind that other applications reading your bar code will interpret your checksum digit as part of the message itself.

Codabar is also known as Ames Code, USD-4, NW-7, or 2 of 7 Code.

A Codabar bar code has the following structure:

1. One of four possible start characters (A, B, C, or D), encoded from the table below.
2. A narrow inter-character space.
3. The data of the message, encoded from the table below, with a narrow inter-character space between each character.
4. One of four possible stop characters (A, B, C, or D), encoded from the table below.

In the following discussion, we represent the encoding of the bar code by treating "1" as a "dark" or "bar" section of the bar code, and "0" as a "light" or "space" section. Thus the sequence 1101 represents a double-wide bar (11), followed by a single-wide space (0), followed by a single-wide bar (1).