Patent ID: 8137894

Claim:
A read-only storage medium having double-layer structure, the storage medium comprising: a first-layer being distant from a light source, the first-layer having a burst cutting area, a system lead-in area, a data lead-in area, and a first data area, the burst cutting area being located inward of the system lead-in area, the system lead-in area being located inward of the data lead-in area, the data lead-in area being located inward of the first data area, and the system lead-in area having a first track pitch larger than a second track pitch of the data lead-in area; and a second-layer having a system lead-out area, a data lead-out area, a second data area, the system lead-out area being located inward of the data lead-out area, the data lead-out area being located inward of the second data area, the system lead-out area having a third track pitch larger than a fourth track pitch of the data lead-out area, and a whole of the data lead-in area and a whole of the data lead-out area overlap each other in a radial direction.