A circuit breaker includes separable contacts, a trip mechanism having an armature mechanism responsive to selected conditions of current flowing through the contacts, and an operating mechanism for opening and closing the contacts. The computer keyboard comprises: a plurality of keys; a detecting unit, which outputs a detecting signal according to the pressing pressure of the plurality of keys; and a keyboard controller, which generates a key code according to the detecting signal and sends the key code to a digital device. The footrest folds into the crash bar to provide a stream lined and custom appearance. When creation of the map is in process, disclosure of the map is prohibited, and all the network devices are notified that creation of the map is in process.