The UK Postal Service is promoting the use of a 4 State barcode to speed mail sorting. This 4 State barcode encodes a variable number of digits and letters and has a checksum appended to the data.
You must make sure you give the correct digits and letters to the BarDIMM, and BarDIMM will calculate and print automatically the checksum.
4 state barcodes must be ended with a regular text font escape sequence.