Parental information of a video program recorded on an optical disk is always checked in a disk player. Even if a jump of laser beam tracing of an optical head erroneously occurs due to shocks or vibrations, the content of parental information assigned to the destination of optical head jumping is checked,...http://www.google.com.hk/patents/US6009433?utm_source=gb-gplus-share專利 US6009433 - Information storage and information transmission media with parental control
