The source of the data to be sorted is provided either directly from a data set or indirectly by a routine (Sort Exit E15) written by the user. Similarly, the destination of the sorted output is either a data set or a routine (Sort Exit E35) provided by the user.
PLISRTA is the simplest of all of the interfaces because it sorts from data set to data set. An example of a PLISRTA program is in Figure 50. Other interfaces require either the input handling routine or the output handling routine, or both.