A DFSORT program phase is a large DFSORT component designed to perform a specific task such as writing the output file. Various user exits are contained in the input and output phases and are activated at a particular time during DFSORT processing. The input phase is used only for a sort or copy. When the output phase is completed, DFSORT returns control to the operating system or invoking program. Figure 1 is a representation of DFSORT input/output logic.

Figure 1. Examples of DFSORT Input/User Exit/Output Logic