MSI is a numeric barcode derived from the Plessey format. It encodes digits as alternating pulse-width patterns with a Modulo-10 checksum appended by default. Scanners decode the check digit and discard it, so the stored value contains only the original digits.
Character set
Digits 0–9. No fixed length constraint; the encoder accepts any numeric string.
Common applications
Retail shelf price labels, library book location codes, and warehouse bin labelling. MSI is less common than CODE128 or ITF-14 in modern supply chains but remains in use in systems installed before those formats became standard.