To provide a recording medium that makes it impossible to delete identification information peculiar to a disk, which is recorded to an optical disk or the like for preventing unauthorized copying, by forming the identification information irreversibly and to form a false mark in a conventional drive, and also provide a method for reproducing the recording medium.
This is a reproducing method for a phase-variable optical disk having a land and a groove to which information can be rewritten. The phase-variable optical disk is provided with a management region which records information by means of a mark irreversibly formed outside the recording region of user data. The irreversibly provided mark is provided continuously and in one united body with the adjacent land and groove with the phase matched. Reproduction data are generated by reading out the management region under a servo-off state, and unauthorized copying is prevented by reproducing the user data based on the reproduction data.
IIDA TAMOTSU
SUGIYAMA TOSHINORI
TAMURA NORIHITO
SHIRAI HIROSHI
YASUI TOSHIAKI
