An extended version of the basic sequential access method (BSAM). When this method is used, a queue is formed of input data blocks that are awaiting processing or output data blocks that have been processed and are awaiting transfer to auxiliary storage or to an output device.; 基本顺序存取法(BSAM)的一种扩充类型。当使用这种存取法时，由正等待处理的输入 数据块或已处理过的并等待向辅助存储器或输出设备传送的输出数据块来形成队列。