backward indicator bit (BIB)
A signal unit (or sequence of bits) that (by changing its status) is used to request retransmission by the remote end whenever it receives a signal unit that is out of sequence. [T1.226-1992]
A signal unit (or sequence of bits) that (by changing its status) is used to request retransmission by the remote end whenever it receives a signal unit that is out of sequence. [T1.226-1992]