A system and method of using of diagnostic procedures through a firmware interface in a processing system are described. Data items each having a first portion and a second portion is stored. An inwardly projecting reinforcing rib is disposed on an inner side of the side wall parallel to and in the immediate vicinity of a rear edge of the door opening. An ambulatory element selectively varies an orientation of the projection grating andor the detection grating to improve the measurement of the level sensor.