Check characters are optional for MSI Plessey and can be added one or two characters, which are calculated values used to verify the integrity of the data. Disable: The scanner transmits MSI Plessey barcodes as it is. Do Not Transmit Check Characters After Verification: The scanner checks the integrity of all MSI Plessey barcodes to verify that the data complies with the check character algorithm. Barcodes passing the checks will be transmitted except the check characters, whereas those failing them will not be transmitted. Transmit Check Characters After Verification: TThe scanner checks the integrity of all MSI Plessey barcodes to verify that the data complies with the check character algorithm. Barcodes passing the checks will be transmitted, whereas those failing them will not be transmitted.