(under subclass 3.1) Subject matter including means for establishing communication in both directions.
(1) Note. Wherein the second communication is the notation or reporting of the program watched or listened to, classification is in audience survey and use accounting.
(2) Note. Wherein any communication in a system is in pulse form, such system is classified elsewhere. See the search notes below.
(3) Note. Wherein any communication in a system is in the form of light waves, such system is classified elsewhere.
SEE OR SEARCH THIS CLASS, SUBCLASS:
2, for audience survey and use accounting.
SEE OR SEARCH CLASS
340, Communications: Electrical, 310.01+, for carrier current or other combined systems without the limitations of this class.
359, Optics: Systems,
109+, for an information signal transmitted between an optical transmitter and optical receiver by means of variation in a characteristic of light waves.
375, Pulse or Digital Communications, for communication in a system in pulse form.
