Délai d'attente de caractère - caractère de contrôle de la transmission, qui doit arriver dans un laps de temps précis. Je ne vois pas bien ce qui n'a pas de sens...
"A specified period of time that will be allowed to elapse in a system before a specified event is to take place, unless another specified event occurs first; in either case, the period is terminated when either event takes place. "
http://en.wikipedia.org/wiki/Timeout_(telecommunication)
"In telecommunications, a negative-acknowledge character (NAK or NACK) is a transmission control character sent by a station as a negative response to the station with which the connection has been set up."
http://en.wikipedia.org/wiki/NAK