group code recording (error code) (GCR)
Group Code Recording (GCR) is a block-oriented algebraic error correction code that can be used to eliminate errors caused by short voltage spikes. The GCR method is used in tape drives such as the QIC drive, among others.
In GCR coding, data is divided into 4 bits and coded into 5-bit words using a value table. So half bytes are converted into 5-bit bit patterns. The parity check has one parity bit on every eight data bits.