Codabar is a simple linear barcode symbol developed in 1972. It is called NW-7, USD-4, Code 2 of 7 (2 values of bar length, 7 elements). It is often used in the medical field (blood bank paper, etc.).

Four bars and three spaces are used for coding. The letters are separated by spaces, and the width of the spaces is a thin stroke. This barcode has four types of start / stop characters. These characters are only used as start / stop characters and do not appear in barcodes.

"Codabar" barcode. "A12345678A" is a barcode-encoded number.