The first or only module of a program coded with the MSP/7 library macros. This module must contain system routines required in every storage load,and can include system routines required by more than one module of the program.

• IBMSystem/7的模块系统程序（MSP/7）库宏指令编码的程序的第一个或唯一一个模块，该模块必须包括每次存储装入所要求的系统例行程序，也可以包括多个程序模块所要求的系统例行程序。