To copy protect an optical disc, such as a DVD, program chains additional to the main program chain are provided. These program chains may lead to the genuine data but in an incomplete or incorrect order or to false data. Sufficient additional program chains are provided to make it difficult to identify the main program chain amongst all of the program chains provided on the disc. The structure of the further program chains ape that of the main program, again to hide the main program chain. The navigation path which leads to the main program chain, and hence to the content on the DVD, is dynamically generated and at least some of the information required to generate the navigational path arises by setting parameters associated with a player or with a user. Thus a search of all of the navigation information on the disc will fail to reveal the navigation path to the content.