1. In a television communications system having a central station for transmitting a plurality of television signals at different frequency channels to a plurality of user stations remote from said central stations, each having a tuner for selecting one of said television signals, a method of utilizing said central station to limit access of said user stations to only certain ones of said television signals, comprising: generating a plurality of category codes at said central station to limit user access to predetermined categories of said television signals, one of said category codes being generated for each user station, each said category code including predetermined enabling data required by the central station for said user station to access said predetermined categories of television signals; transmitting each of said category codes from the central station to its respective user station to precondition each user station by authorization from the central station to selectively access said predetermined categories of television signals; generating a plurality of program codes at said central station to limit user access to said predetermined categories of television signals, one of said program codes being generated for each television signal, each of said program codes including predetermined control data for enabling access to one of said television signals; transmitting one of said program codes with each of said television signals to each of said user stations being tuned to receive one of said television signals; comparing the control data of said program code to the enabling data of the category code provided by the central station to each user station; and enabling only each user station which has a category code with enabling data corresponding to the control data of said program code, whereby said enabled user station can receive and process any said tuned television signal within a predetermined category of said television signals corresponding to said category code.