The Landing Operating Panel (LOP), also called the hall call panel or floor call station, is the push-button panel installed at each floor level outside the elevator that allows waiting passengers to call the elevator. In simplex (single-car) systems, a typical LOP has one or two buttons (up/down arrows); in more complex group systems, LOPs may include a floor indicator display. LOPs are wired to the controller and must be accessible to wheelchair users per accessibility standards (mounting height, Braille markings).