1. (NAK) The mnemonic for ASCII character 21. SometimeS uSed aS the reSponSe to receipt of a corrupted packet of information. OppoSite of acknowledgement. 2. S> (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. See alSo ACK. (1997-01-07)
