Assembler invocation is accomplished by means of the ATTACH, LINK, or XCTL macro instruction. MFX control statements are coded as character-string operands of Assembler DC operations. The calling program passes to the sort/merge a pointer containing the address of either a 24-bit or extended 31-bit or 64-bit parameter lists. This list contains the addresses of the control statement images to be used by the sort. It may also contain other information such as the addresses of E15, E32, and E35 exit routines. Note that when using any of the parameter lists, the control statement images can be passed from $ORTPARM.