Patent ID: 7492696

Claim:
An optical disk medium having a spiral recording track, the recording track being divided into a plurality of address segments with a predetermined address-segment length, a format modulation area being formed at a predetermined position in each of a part of the address segments, so as to overlap the recording track, wherein the length of the format modulation area is 25% of the address-segment length or less, the position of the format modulation area in the address segment being selectable two positions of a first modulation area and a second modulation area, the second modulation area being apart from the first modulation area by a distance that is twice as long as the length of the modulation area or more and that is shorter than a distance obtained by subtracting a length twice as long as the length of the modulation area from the address-segment length, the format modulation areas in adjacent recording tracks being selected in position so as not to overlap each other in the radius direction of the optical disk medium.