Sometimes used as the response to receipt of a corrupted
2. communications (NAK) Any message transmitted to indicate
that some data has been received incorrectly, for example it
may have a
checksum or message length error. A NAK message
allows the sender to distinguish a message which has been
received in a corrupted state from one which is not received
at all.
An alternative is to use only
ACK messages, in which case
the non-receipt of an ACK after a certain time is counted as a
NAK but gives no information about the integrity of the
communications channel.
(1997-01-07)