Code 39 is a discrete bar code, meaning that a fixed pattern of bars represents a single character. Each character is made up of 9 bars - 3 of which are wider than the others. A single character therefore consists of 5 black bars and 4 white bars. Code 39 can encode numbers 0-9, the uppercase alphabet A-Z, SPACE, and the following symbols: - . * $ / % +.

A denser, more compact symbology that supports the lower 128 ASCII characters. Used whenever space is at a premium. Each data character encoded in a Code 128 symbol is made up of 11 black or white modules. Three bars and three spaces are formed out of these 11 modules. Bar and spaces can vary between 1 and 4 modules wide.