| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk which tactually discriminates the top and bottom of the optical disk and the kind of a number of disks with a simple constitution. SOLUTION: A recessed part 14 is disposed outside an information area and the recessed part is disposed so as to reach one side surface of the surface and the back surface of disk, and the outer peripheral edge surface 15 of disk. By disposing the recessed parts in plural pieces on the one side surface, the top and bottom (surface A and surface B) and the kind of disk can be discriminated. |
