A disc-shaped information recording medium includes a laminate of recording layers on and from which an information signal can be optically recorded and reproduced from one side of the medium. Data areas are provided in the recording layers, respectively. The information signal can be recorded on and...http://www.google.com.au/patents/US7680020?utm_source=gb-gplus-sharePatent US7680020 - Method of recording a signal on an information recording medium, and method of recording and reproducing a signal on and from an information recording medium
