A string of characters accepted by the system as a single block of input from a terminal, for example, all characters entered before a carriage return or all characters entered before the terminal user hits the attention key.

• 系统从一个终端作为单个输入信息组而接收的一串字符。例如，回车前键入的所有字符或终端用户敲击注意键之前键入的所有字符。