In telecommunication, a longitudinal redundancy check (LRC), or horizontal redundancy check, is a form of redundancy check that is applied independently to each of a parallel group of bit streams. The data must be divided into transmission blocks, to which the additional check data is added.
The term usually applies to a single parity bit per bit stream, calculated independently of all the other bit streams (BIP-8).[1][2]
This "extra" LRC word at the end of a block of data is very similar to checksum and cyclic redundancy check (CRC).