a receiver for a television transmission system of the kind in which some of the line scan periods of a conventional transmission that are left blank between successive frame transmissions are utilized for signalling data for selective display on the screen of a television receiver . the information to be displayed as a line of data may be transmitted in a single line scan period . this is achieved by transmitting in a line scan period a page number and then in subsequent line scan periods the lines of data for that page . new page numbers are then transmitted followed by their respective lines of data in sequence . the receiver selects a desired page of data by identifying the desired transmitted page number and then recording all lines of information subsequent to that page number until it identifies a further page number whereupon it ceases to store any further information .