A method of transmitting data that includes a plurality of data streams in a wireless broadcast system, the method comprising: mapping the plurality of data streams onto a super-frame that includes a plurality of frames, each frame including a preamble section and a data section, the preamble section and the data section being time-multiplexed, the data section carrying at least parts of said plurality of data streams, and the preamble section carrying at least signalling information; inserting, in a configuration signalling field of the preamble section of each of the plurality of frames, a number of the plurality of data streams mapped onto the super frame and a number representing a limit applicable to each of the plurality of frames; inserting signalling information in a first signalling information field of the preamble section of a given frame for assisting in the reception of a first number of said plurality of data streams for the given frame, the first number being less than or equal to the number representing the limit applicable to each of the plurality of frames, the first signalling information field being of a size that is the same for each of the plurality of frames, and the number representing the limit identifying a limit to the number of data streams for which signalling information can be carried in the first signalling information field; if the number of data streams for the given frame is greater than the number representing the limit, inserting signalling information in a second signalling information field of the preamble section of the given frame that assists in the reception of further of said plurality of data streams for the given frame, the second signalling information field being of a variable size; inserting said first and second signalling information fields in the preamble section of said given frame; and transmitting the plurality of frames. mapping the plurality of data streams onto a super-frame that includes a plurality of frames, each frame including a preamble section and a data section, the preamble section and the data section being time-multiplexed, the data section carrying at least parts of said plurality of data streams, and the preamble section carrying at least signalling information; inserting, in a configuration signalling field of the preamble section of each of the plurality of frames, a number of the plurality of data streams mapped onto the super frame and a number representing a limit applicable to each of the plurality of frames; inserting signalling information in a first signalling information field of the preamble section of a given frame for assisting in the reception of a first number of said plurality of data streams for the given frame, the first number being less than or equal to the number representing the limit applicable to each of the plurality of frames, the first signalling information field being of a size that is the same for each of the plurality of frames, and the number representing the limit identifying a limit to the number of data streams for which signalling information can be carried in the first signalling information field; if the number of data streams for the given frame is greater than the number representing the limit, inserting signalling information in a second signalling information field of the preamble section of the given frame that assists in the reception of further of said plurality of data streams for the given frame, the second signalling information field being of a variable size; inserting said first and second signalling information fields in the preamble section of said given frame; and transmitting the plurality of frames.