A BSC protocol exchange in preparation for the transmitting and also the receiving data. The transmitting station transmits an ENQ character, and the receiving station acknowledges the receipt of the ENQ character by sending an ACK0 control character.

• 二元同步通信（bsc）规程的一种协议交换过程，在准备发送和接收数据时进行。发送站发送一个ENQ字符，接收站在接收到该字符后发送出一个ACK0控制字符表示认可。参阅bid。