Interleaved 2 of 5 is a variable length (must be a multiple of two), high-density, self-checking, numeric bar code that uses five black bars and five white bars to define a character. Two digits are encoded in every character; one in the black bars and one in the white bars. Two of the black bars and two of the white bars are wide. The other bars are narrow.

Each Interleaved 2 of 5 bar code contains an even number of characters, and consists of the following elements:

• Leading quiet zone

• Start character

• Data characters

• Optional check character

• Stop character

• Trailing quiet zone

In some cases, random patterns on an image can inadvertently be detected as Interleaved 2 of 5 bar codes. To avoid this, you should set the minimum number of characters in the bar code to at least 3 when searching for Interleaved 2 of 5 bar codes. Also, Interleaved 2 of 5 bar codes cannot be properly read when overlaid on a starburst pattern.

An example of an Interleaved 2 of 5 bar code is shown below: