The sort/merge can be invoked by an executing program written in COBOL, PL/1 or assembler language. However, since most invoked sorts utilize inline exits (typically through the COBOL SORT verb) and so are handicapped by the calling program’s I/O techniques and memory allocations, sort performance may be degraded by this mode of initiation. Whenever performance is an important consideration, the sort should be initiated through the EXEC job control statement. Additional programming flexibility is provided by exits which can be separately compiled and link-edited. These may be coded in COBOL, FORTRAN, REXX, and assembler language. Exits may also be written in PL/1 provided that MFX is invoked by a PL/1 program.