21 [ ELECTRONIC AMPLIFIERS; ] ELECTRICAL POWER SUPPLIES; [ AUDIO FREQUENCY OSCILLATORS; CODED CURRENT TRANSMITTERS; CODED CURRENT DECODING UNITS; LINE CIRCUIT CARRIER MODULATORS; TUNED ELECTRICAL ALTERNATORS; BATTERY CHARGE CONTROL UNITS; ] AUDIO FREQUENCY OVERLAY TRACK CIRCUIT RECEIVERS; [ ELECTRICAL SWITCHES; ] [ ELECTRICAL INDUCTORS; ] ELECTRICAL TRANSFORMERS; ELECTRICAL REACTORS; [ ELECTRICAL CONDENSERS; ] ELECTRICAL RELAYS; [ ELECTRICAL RELAY SNUB UNITS; ] [ COPPER OXIDE AND SELENIUM DRY CONTACT RECTIFIERS; ] [ ELECTRICAL PLUG CONNECTORS; ] [ ELECTRICAL NETWORK SUBASSEMBLIES- NAMELY, RESONANT UNITS, ARC SUPPRESSORS, INTERSTAGE COUPLING UNITS, ELECTRICAL INTERFERENCE SUPPRESSORS, PASSIVE NETWORKS, BUFFER COILS ANDPHASE SHIFT NETWORKS;] [ ELECTRICAL FILTERS AND PARTS THEREFOR; ] [ LOUDSPEAKERS; ELECTRICAL CONTACTORS; ] LIGHTNING ARRESTERS; [ ELECTRIC MOTORS; ELECTROMECHANICAL AUDIBLE INDICATORS; VOICE OPERATED CALLING DEVICES; TRAIN COMMUNICATION SYSTEMS; TELEPHONE COMMUNICATION APPARATUS OF THE MODULATED CARRIER WAVE TYPE, AND AUDIAL AND VISUAL INDICATING CALL DETECTORS THEREFOR; VOICE AND/OR CODE MODULATED CARRIER COMMUNICATION AND/OR CONTROL EQUIPMENT, AND COMPONENTS THEREOF- NAMELY, TRANSMITTERS, RECEIVERS, MODULATORS, AND CODE REPEATERS; MULTIPLEX CODE CONTROL SYSTEMS; DATA DISPLAY AND TRANSFER SYSTEMS; CHANNEL SELECTORS FOR MULTIPLE INDICATION, MULTIPLE CHANNEL LOCOMOTIVE CAB SIGNAL SYSTEMS; ELECTRONIC SYSTEMS FOR INDICATING AT A STATION PLATFORM PRIOR TO THE ARRIVAL OF A TRAIN THE ORIGIN, DESTINATION AND/OR CLASS OF THE TRAIN; HERMETICALLY SEALED AND POTTED TRANSFORMERS AND/OR CHOKE COILS; ] INTERLOCKING SYSTEMS FOR RAILWAYS; RAILWAY SIGNALING AND/OR CONTROL SYSTEM, [ SECTIONALIZING UNITS; ] [ TRAIN CONTROL SYSTEMS AND PARTS THEREFOR- NAMELY, REVERSING SWITCHES, EQUIPMENT BOXES AND RECEIVER COILS; OFFICE LINE, OFFICE AND/OR FIELD CODING UNITS, AUXILIARY LINE UNITS, FIELD AND/OR LINE STORAGE UNITS, REMOTE CODE INDICATION SYSTEMS, INDICATION REGISTRY UNITS, AND ETCHED TRAIN GRAPH PANELS FOR CENTRALIZED RAILWAY TRAFFIC CONTROL SYSTEMS; ] [ CAR RETARDER SYSTEMS; ] [ ELECTRIC SWITCH AND LOCK MOVEMENTS; ] ELECTRIC SWITCH LOCKS; [ RAILWAY SLIDE DETECTORS; ] IMPEDANCE BONDS FOR RAILWAY TRACK CIRCUITS; [ DRAW BRIDGE CIRCUIT CONTROLLERS; ] HIGHWAY CROSSING SIGNALS; ELECTRICALLY OPERATED HIGHWAY CROSSING BELLS; [ RAILWAY WAYSIDE VISUAL MOTOR CAR INDICATORS; ] RAILWAY WAYSIDE AND/OR OVERHEAD VISUAL SIGNALS- NAMELY, LIGHT SIGNALS, DWARF SIGNALS AND SEARCHLIGHT SIGNALS; LOCOMOTIVE CAB SIGNALS; EQUIPMENT BOXES FOR TRAIN CONTROL SYSTEMS; [ RELAY AND/OR FILTER AND/OR INSTRUMENT CASES, RACKS, PANELS AND/OR HOUSSINGS AND JUNCTION AND TERMINAL BOXES; ]