You can define and use a symbol for any field or constant in the following DFSORT control statements: INCLUDE, INREC, JOINKEYS, MERGE, OMIT, OUTFIL, OUTREC, REFORMAT, SORT and SUM. You can use a symbol for a number associated with various keywords in the following DFSORT control statements: INREC, JOINKEYS, MERGE, OPTION, OUTFIL, OUTREC and SORT. You can also use a symbol for an output column in the following DFSORT control statements: INREC, OUTFIL and OUTREC. This makes it easy to create and reuse collections of symbols (that is, mappings) representing information associated with various record layouts. You can use system symbols (for example, &JOBNAME.) in your symbol constants. You can use SET and PROC symbols in your symbol constants. See Using symbols for fields and constants for complete details.