在编目或流内过程中使用的一种作业控制语句，可用来对包含在过程中的符号参数赋予系统设定值。对流内过程，用来标志过程的开始。 A job control statement used in cataloged or in-stream procedures. It can be used to assign default values for symbolic parameters contained in a procedure. For in-stream procedures, it is used to mark the beginning of the procedure.
氨气、煤焦油、焦煤都是煤气生产过程中的副产品。 Ammonia, coal tar and coke are all by-products obtained in the manufacture of coal gas.
