In a SAP customer function you sometimes want to refer to data from the calling program (if this data is not part of the function interface). A function group has its own global data area.
Using the following syntax for field-symbols it is possible to do just this. => calling program is SAPMV45A => Field we want to refer to is YVBAK-BSTNK This same logic also works for external subroutines but of course not for SUBMIT. Code: FIELDNAME = '(SAPMV45A)YVBAK-BSTNK'. ASSIGN (FIELDNAME) TO