when an act is carried out, the system triggers the PROCESS AFTER INPUT event. The data passed includes field screen data filled by the user and a function code. Function code is a technical name that has been allocated in a screen Painter or Menu Painter to a menu entry, a push-button, the ENTER key or a function Key of a screen. An internal work field(ok-code)in the PAI module weigh up the function code, and the suitable action is taken.