To confirm that a message or signal has been received such as by the pressing of a button or the selection of a software command.
(1.) To answer. To respond to a poll, address, or message. (2.) In the X.25 API, to confirm that a data packet with the D-bit set has arrived.
A message sent by the intersection manager to driver agents to acknowledge the receipt of a Cancel or Reservation-Completed message. Once a driver agent has received this message after sending a Cancel message, it knows that the reservation it held previously has been cancelled and it is free to send a new Request message.