vertical redundancy check (VRC)
Cross-parity, Vertical Redundancy Check(VCR), is an error protection method in data transmission based on the cross sum.
On the transmit side, the checksum is determined for each transmitted character and a parity bit is added. On the receive side, each character of an ASCII block ischecked using the parity bit. It is irrelevant for the parity check whether an even or an odd parity is selected. With even parity the cross sum results in an even number, with odd parity in an odd number.
With the cross parity only one erroneous bit in a data word can be detected. If two errors occur at the same time, the procedure does not detect an error because the parity is correct.