The symbol comprises the following elements:

• Data regions that contain square modules in an array

• Alignment patterns (for larger symbols)

• Finder pattern

• Quiet zone border

The finder pattern around the perimeter of the symbol consists of a solid line on the left and bottom edges and a pattern of alternating black and white modules along the right and top edges.

This symbology supports the C40 Basic character set, which includes the following alphanumeric characters:

• All numeric digits (0-9)

• All uppercase letters (A-Z)

• Space character

The C40 character set must be used for the data that is in the Royal Mail-defined portion of the barcode. The customer-defined content is not limited to this character set.

Data Matrix ECC 200 symbols use the Reed-Solomon algorithm for error correction.

The size of a Data Matrix symbol depends on the amount of data that is entered. The CMDM implementation uses the following Data Matrix types:

• Type 7 (24 x 24 modules)

• Type 9 (32 x 32 modules)

• Type 29 (16 x 48 modules)

The module size must be in the range from 0.5 - 0.7 mm (0.019 - 0.027 inches). Data Matrix requires a four-module-wide quiet zone on all sides.