A user defined routine composed of subroutines necessary to prepare a message segment for processing, and examine and process the control information in the message segment. The functions performed are based on the user-selected macroinstructions that determine the configuration of each line group routine. One line group routine must be provided for each line group included in the system.; 一种用户定义的程序,由若干子程序组成,这些子程序对准备待处理的报文段、 对检查及处理报文段中的控制信息都是必需的。所实现的功能都建立在用户选定的宏指令 基础之上,它们决定了每个线组程序的结构。必须为系统的每个线组提供一个线组程序。