The following describe a part of an elevator behavior. The elevator has a set of buttons (one for each floor). These buttons illuminate when pressed and cause the elevator to stop at the corresponding floor. Each floor, except the first and top floors, has two buttons, one to request an elevator traveling up (up-button) and one to request an elevator traveling down (down-button). The first floor only has an up-button and the top floor only has a down-button. These buttons illuminate when pressed. The illumination is canceled when the elevator stops at the floor traveling toward the desired direction. For security reason, when the charge carried by the elevator is superior or equal to some threshold value, the elevator won't stop at a floor unless there is a request from within the elevator to stop at that floor. The elevator always stops at the top floor when traveling up, and at the first floor when traveling down. This problem concerns the elevator controller behavior when approaching a floor. The elevator has a sensor that is triggered as it nears each floor. The elevator controller must then decide whether or not to stop the elevator at that