For in-stream procedures, it is used to mark the beginning of the procedure.
对流内过程，用来标志过程的开始。
2
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.
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。
3
Expound main features, welding procedure and application of high purity and super purity stream-conveying in semiconductor, pharmaceutical and biology Engineering of polymer pipeline.