Codabar characters are encoded using four bars and three spaces. The bars are of varying widths — two wide and two narrow, giving rise to the “2 of 7” designation. Codabar also uses a fourth space, called the “intercharacter space” which separates barcode characters but does not form part of characters themselves.
This barcode format contains five key elements:
- A Leading Quiet Zone
- One Start Character Represented by the Letter A, B, C or D
- Encoded Symbol Characters Using a 2 of 7 Methodology
- One Stop Character of A, B, C or D
- A Trailing Quiet Zone
Available Codabar characters include the numbers 0-9 and six symbols:
It’s also worth noting that while every Codabar barcode must contain a pair of start/stop symbols, there’s no requirement for these symbols to be identical. If “A” is the start character, any of B, C, or D could act as the stop character. This lack of standardization is one reason for the shift away from Codabar, since differing start/stop patterns could lead to confusion around character encoding and potentially lower barcode integrity.