ABAP Programs: Classifying parameters

REPORT ZSOURCE1005.

* Data declarations for later use
DATA: A1 TYPE P VALUE 2,
A2 TYPE P VALUE 4,
A3 TYPE P VALUE 8.
* Calling a form with different parameter types
PERFORM CALC USING A1
A2
CHANGING A3.
* Displaying the result

WRITE A3.
* Defining a form with different parameter types
FORM CALC USING VALUE(F1) LIKE A1
F2 LIKE A2
CHANGING VALUE(F3) LIKE A3.
F3 = F1 + ( F2 * F3 ).
ENDFORM.