Patent ID: 8027237

Claim:
An optical storage medium in which main information in a format including sectors, each of the sectors being provided with address information and composed of frames, each of the frames being provided with synchronous codes, is recorded as means of optically readable recording marks, wherein sub-information is recorded by a displacement of the recording marks in a radial direction, the displacement being implemented by forming the recording marks so as to be displaced toward an outer rim side of the optical storage medium or toward an inner rim side relative to a standard position, the sub-information is recorded at a portion in the sectors except an area in which a fixed pattern for frame synchronization is recorded in the synchronous codes and an area of a frame that is located at head of each sector, the displacement of the recording marks is according to a pseudo random number sequence generated based on a recording position of the synchronous code in the frame, and the pseudo random number sequence is generated by setting an initial value for each sector, the initial value being generated based on the address information in a sector at which the sub-information is recorded.