NEGATIVE ACKNOWLEDGE CHARACTER (NAK)

A transmission control character sent by a station as a negative response to the station with which the connection has been set up. ( 188 ) 188 ) Note 1: In binary synchronous communication protocol , the NAK is used to indicate that an error was detected in the previously received block and that the receiver is ready to accept retransmission of that block. Note 2: In multipoint systems, the NAK is used as the not-ready reply to a poll.