```abap methods EXECUTE importing !IR_OPERAND1 type ref to DATA !IR_OPERAND2 type ref to DATA !IR_RESULT type ref to DATA. METHOD execute. CHECK ir_operand1 IS BOUND AND ir_operand2 IS BOUND AND ir_result IS BOUND. ASSIGN ir_operand1->* TO FIELD-SYMBOL(<operand1>). ASSIGN ir_operand2->* TO FIELD-SYMBOL(<operand2>). ASSIGN ir_result->* TO FIELD-SYMBOL(<result>). TRY. <result> = <operand1> - <operand2>. CATCH cx_root. ENDTRY. ENDMETHOD. ``` I found this method which treats an importing parameter as if it were changing/returning.