Apparatus comprising: means for receiving a data signal on a first communication channel comprising a data system stream including a main data stream comprising first data encoded in a first encoding format for representing a video program and including an additional data stream comprising second data encoded in a second encoding format indicating the availability of additional information related to the video program, wherein the second data encoded in said second encoding format is embedded in the main data stream representing the video program; means for providing the first data encoded in the first encoding format for representing the video program to a display device; means for extracting the second data indicating the availability of additional information from the data system stream; means (78, 82) for providing the second data indicating the availability of additional information to at least one predetermined remote communication unit for display on said at least one remote communication unit (30, 32); means for receiving from said at least one remote communication unit a request for the additional information; means (78, 90) for requesting from a service provider said additional information via a second communications channel other than the first communications channel; means for receiving the additional information on the second communication channel; and means (78, 82) for providing the additional information to said at least one remote communication unit (30, 32); means for decoding the first data stream representing the video program to produce decoded data, and means for producing a display of the video program in response to the decoded first data, wherein the second data indicating the availability of additional information related to the video program comprises an external object of additional information relating to the video program, and the external object becoming unavailable with the video program being finished. means for receiving a data signal on a first communication channel comprising a data system stream including a main data stream comprising first data encoded in a first encoding format for representing a video program and including an additional data stream comprising second data encoded in a second encoding format indicating the availability of additional information related to the video program, wherein the second data encoded in said second encoding format is embedded in the main data stream representing the video program; means for providing the first data encoded in the first encoding format for representing the video program to a display device; means for extracting the second data indicating the availability of additional information from the data system stream; means (78, 82) for providing the second data indicating the availability of additional information to at least one predetermined remote communication unit for display on said at least one remote communication unit (30, 32); means for receiving from said at least one remote communication unit a request for the additional information; means (78, 90) for requesting from a service provider said additional information via a second communications channel other than the first communications channel; means for receiving the additional information on the second communication channel; and means (78, 82) for providing the additional information to said at least one remote communication unit (30, 32); means for decoding the first data stream representing the video program to produce decoded data, and means for producing a display of the video program in response to the decoded first data, wherein the second data indicating the availability of additional information related to the video program comprises an external object of additional information relating to the video program, and the external object becoming unavailable with the video program being finished.