General Function Module Call
1. CALL FUNCTION func {
parameter_list
| parameter_tables }.
Call of Function Module Exit
2. CALL CUSTOMER-FUNCTION function_exit
parameter_list.
Registration of an Update Task Function Module
3. CALL FUNCTION update_function IN UPDATE TASK
[EXPORTING p1 = a1 p2 = a2 ...]
[TABLES t1 = itab1 t2 = itab2 ...].
Remote Function Call
4. CALL FUNCTION ... DESTINATION ...
Call or registration of a function module. A function module is always specified dynamically. The identifier of the called function module is always determined at runtime. Before release 6.10, parameters could only be passed on statically. As of release 6.10, you can dynamically assigned the current parameters to the formal parameters of a generally called function module.
System fields
When a function module is called, the system field sy-subrc is set to 0. If a non-class-based exception occurs that is handled by assigning a value, sy-subrc is set to this value.