These requirements cover discrete electrical control units@ communication units@ distributed recipient mass notification control units and dedicated targeted individual receiving equipment@ high power speaker arrays@ transport products which manipulate the data packets@ and accessories for mass notification systems to be employed in accordance with the National Fire Alarm Code@ NFPA 72. The products covered by this outline are intended to be used in combination with other appliances and devices to form an emergency communication and/or mass notification system. These products are intended to communicate critical information within buildings and/or outdoor areas about emergencies including but not limited to terrorist activities@ other dangerous situations@ accidents@ natural disasters and the like. Communication is through voice instructions@ as well as alert and evacuation signals. An installation document(s) provided with the product describes the various products needed to form an emergency communication and/or mass notification system and their intended use and installation. These requirements also do not address two-way emergency service personnel communication systems. Audible notification appliances are to be assessed to the Standard for Audible Signaling Appliances@ UL 464. Visible notification appliances are to be assessed to the Standard for Signaling Devices for the Hearing Impaired@ UL 1971@ or the Standard for Visual Signaling Appliances ?C Private-Mode Emergency and General Utility Signaling@ UL 1638@ as applicable. Textual visible appliances are to be assessed to UL 1638. Products incorporating fire and/or security signaling functions are to be assessed to the UL standards applicable to their intended function and application.