Information for imposing copy generation restrictions is superimposed in the format of an XDS signal that is according to the standard of a closed caption broadcast so as to permit performance of copy generation restriction in response to such information without the need to change the structure...http://www.google.com.au/patents/US5822425?utm_source=gb-gplus-sharePatent US5822425 - Methods of transmitting and recording television signals with copy generating restriction information and recording apparatus therefor 
