1. A CATV data transmission method, in which data is transmitted from a transmitting side to a receiving side having a first plurality of individual terminal units, each of said units having assigned an individual address, comprising: assigning said terminal units to a second plurality of groups, each of said groups containing one or more of the terminal units, that receive collectively data transmitted from said transmitting side and are intended for each terminal in said group; assigning a unique group address to each of said groups, thereby defining a second plurality of group addresses; storing at each terminal unit a reference signal and at least two addresses, comprising an individual address and any applicable unique group addresses, said stored applicable unique group addresses comprising all of the unique group addresses for those of said groups to which said terminal unit is assigned; transmitting from said transmitting side to all terminal units in common at said receiving side, a transmitted signal comprising at least (i) data intended for an individual terminal unit together with an individual address and a group address pattern, comprising at least one of said unique group addresses, or (ii) data intended collectively for one of said second plurality of groups together with a group address pattern, comprising at least one of said unique group addresses; at each terminal unit, receiving at least said transmitted data and said group address pattern; in each terminal unit: initially comparing a portion of said received group address pattern with said reference signal and generating a first signal if said portion and said reference signal are identical and generating a second signal if said portion and said reference signal are not identical; comparing a stored individual address with said transmitted signal in response to the generation of said first signal; comparing all of said stored unique group addresses with said transmitted signal in response to the generation of said second signal; and, if coincidence is obtained in either of said address comparisons, processing at said terminal unit said data.