It was asked of me to mention the "HOLD" position. This position in most elevator cars allows the crew to place the key in the "HOLD" position and exit the car without it getting recalled to the lobby. When the crew gets back in the car they need to turn back to the "ON" position and take full control of the car again.
The "BYPASS" position is at the lobby control. This can be used to put the elevator back into normal operation if the alarm system has not reset. This should be done only after it as been determined that the alarm activation is a malfunction or service related.
Hope that helps.