The Royal Mail 4-state barcode is used for automated mail sort process. Encoding is carried out in alphanumeric format (0-9, A-Z). There are 38 valid characters in the entire character set:

 

Valid symbols:

numeric characters 0-9;

alpha characters A-Z

Length:

Variable

Check digit:

none

 

 

A barcode consists of four bars and divided into 3 regions, two of them are ascenders and two descenders. The tracking region is present in all bars. The picture below shows the structure of the Royal Mail 4-state barcode:

 

 

Ascending Region;

Tracking Region;

Descending Region.

 

 

A Royal Mail 4-state Barcode. "1234567890123" is a number encoded in the barcode.