In Systems Network Architecture ( SNA ), an operational mode in which the receiver responds to request units on a given normal flow in the order it receives them ; i. e., in a first-in, first-out sequence.

• 系统网络体系结构(SNA)中的一种工作方式,在此方式下,接收端按照它接收的顺序,即先进先出顺序,响应给定的正常信息流上的请求单元。