Royal Mail 4 statusBarcodes are used for automated email sorting. Encoding is performed in alphanumerical format (0-9, AZ). There are 38 valid characters in the entire character set.
| Valid symbols: | Numbers 0-9; Alphabet A-Z |
| length: | variable |
| Check digit: | none |
Barcodes consist of four bars, divided into three areas, two of which are ascenders and two descenders. The tracking area is on every bar. The following figure shows the structure of the Royal Mail 4-state barcode.
Ascending area;
Tracking area;
Descending area;
Royal Mail 4-state barcode. "1234567890123" is a barcode-encoded number.
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