MSI Plessey
Derived from the Plessey Code developed in Britain, MSI Plessey encodes numeric data only and has spent most of its working life on supermarket shelf-edge labels and inventory tags rather than on products themselves. The Plessey Company released the original in 1971. Its distinguishing flexibility lies in the check digit: an implementation may append a Mod 10 digit, a Mod 11 digit, or two digits combining both schemes, trading symbol length against detection strength. Length is otherwise unconstrained. A 0.19 mm X-dimension and ten-module quiet zones are conventional. MSI Plessey is not a GS1 data carrier and defines no data structure, and it has largely been displaced by Code 128 wherever alphanumeric capability or supply-chain interoperability matters.
A numeric-only barcode derived from the original Plessey Code, primarily used for supermarket shelf marking and inventory control. MSI offers multiple check digit schemes (Mod 10, Mod 11, or combined) making it adaptable to different accuracy requirements.