Msi Barcode is a barcode developed by MSI Data Company. It is based on the original Plessy symbology. As such, the "Msi" barcode is sometimes called a "Modified Plessey". A basic implementation of Msi barcodes is used for warehouse shelves and inventory.

Msi is a variable length sequential code and can display digits 0..9. One or two check digits calculated by modulo-10 or modulo-11 algorithms can be used for control. Each barcode symbol has four elements. Elements consist of strokes and gaps and are 3 units wide. If the element represents binary 0, the stroke width is 1 module and the gap is 2 modules. Conversely, if the element represents a binary 1, the stroke is 2 modules wide and the gap is 1 module. So each character is 12 modules wide. Therefore, the data density of this barcode is very low.

“Msi” barcode. "1234567890" is the number encoded in the barcode.