861	 Read-Backward Polyphase Sorting	 Read-backward Polyphase sorting provides more efficient use of the tapes available to a sort than most other sorting techniques. Backward Polyphase produces a continuous merging process from n- tapes where n is the total number of tapes being used in the sorting process. Any of the available presorting techniques may be used in conjunction with the Polyphase merge sort provided that the presort has the capability of producing both ascending and descending strings and distributing the strings on the various tapes as required by the Polyphase Merge.
