Royal Mail 4-State Customer Code

This symbology supports the alphanumeric characters 0 through 9 and capital A through Z.

The minimum possible length of this symbology is 35.98mm which is a 5 digit code including start and stop bars, a delivery point suffix, and a checksum digit at 24 bars per inch. The maximum possible length is 68.58mm which uses a 7 digit code, start and stop bars, an international prefix, a delivery point suffix, and a checksum digit at 20 bars per inch. The required quiet zone is 2mm all around the barcode. The density of the code is 20 to 24 bars per 25.4mm. All bars must be equally spaced apart.

Each complete barcode will contain distinct bars and spaces for each character as well as a start and stop bar, a checksum digit, and quiet zones on all sides of the barcode.

Each character is made up of 4 separate bars. Each bar can be in one of four "states", thus the name of the symbology. The four states are "tracker", "tracker, ascender", "tracker, descender", and "tracker, ascender, descender" and are illustrated in the diagram below.

These bars help identify where the barcode begins and ends as well as its orientation. The start bar is a single tracker, ascender bar. The stop bar is a single tracker, ascender, descender bar.

In order to correctly position a Royal Mail Barcode, it must be within the following margins.

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

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

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

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

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