26 INDICATING APPARATUS FOR VEHICLES-NAMELY, TACHOMETERS, HOURMETERS, COMBINATION HOURMETERS AND TACHOMETERS, COMBINATION SPEEDOMETERS AND TACHOMETERS [ ; ELECTRONIC MONITORING AND CONTROL GROUND SUPPORT EQUIPMENT FOR AEROSPACE COMMAND GUIDANCE SYSTEMS; SPACEBORNE ELECTRONIC NAVIGATION SYSTEMS; AND ELECTRICAL TESTING EQUIPMENT-NAMELY, BINARY SIGNAL GENERATORS FOR GROUND AND AIRBORNE SPACECRAFT COMMUNICATIONS AND COMMAND SYSTEMS ]