The block check character( BCC) is a block-specific check sequence that is added to the data transmission block. The transmitted block check character is used for error detection in the transmitted user data and control blocks.
Depending on the protocol, the block check character is generated on the transmitting side from the user data and possibly additionally from the header data and appended to the data block during transmission. The receiving station uses the same algorithm and calculates the block check character from the received data blocks, which it compares with the received block check character. In case of faulty transmission, both block check characters differ from each other.
Error protection procedures corresponding to the determination of parity bits are used in the formation of the block check character. Comparable error detection procedures are Frame Check Sequence( FCS) and Block Check Sequence( BCS).