The symbol comprises the following elements:

• Leading quiet zone

• Start bar (a single tracker, ascender bar)

• Symbol characters that represent data

• Check digit

• Stop bar (a single tracker, ascender, descender bar)

• Trailing quiet zone

The data characters represent sorting rules and other information. Each character is made up of four separate bars. The term "4-state" is derived from the fact that each bar in this symbology is in one of four states. The names of the four states are as follows:

• T (tracker)

• D (tracker, descender)

• A (tracker, ascender)

• H (tracker, ascender, descender)

These are illustrated in the following diagram:

CBC encodes inward Postcodes, outward Postcodes, and the Delivery Point Suffix in any one of seven formats.

This symbology supports the following alphanumeric characters:

• All numeric digits (0-9)

• All uppercase letters (A-Z)

• Opening and closing parentheses (())

CBC contains a check digit that is based on the modulo 6 (mod 6) algorithm.

The minimum length of this symbology is 35.98 mm (when encoding a five-digit code that includes start and stop bars, a delivery point suffix, and a check digit at 24 bars per inch). The maximum length is 68.58 mm (when encoding a seven-digit code that includes start and stop bars, an international prefix, a delivery point suffix, and a check digit at 20 bars per inch). The density of the code is 20 to 24 bars per 25.4 mm. All bars must be evenly spaced.

CBC requires a quiet zone space of at least 2 mm on all sides.

To correctly position a CBC barcode, it must be within the following margins:

• No less than 18 mm up from the bottom edge of the piece of mail

• No more than 120 mm up from the bottom edge of the piece of mail

• No less than 15 mm down from the top edge of the piece of mail

• No less than 15 mm from either side of the piece of mail

The barcode may be printed at 0, 90, 180, or 270 degrees.