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.