A sequence of binary digits including data and call control signals that is switched as a composite whole. The data, call control signals, and possibly error control information, are arra nged in a specific format.

• 一种包括数据和呼叫控制信号的二进制数字的序列，它是作为一个整体进行交换和传送的。其中数据、呼叫控制信号以及可能有的差错控制信息按照规定的格式进行安排。