An optical disc includes a processed area that has been processed by the irradiation
of a YAG laser. Concave pits and convex pits having a length 3T-14T (T=0.133 m)
are formed in an area of the optical disc other than the processed area. The processed
area includes (1) a concave pit having a length X or (2) a pit string that has
a length X and includes a convex pit from which a reflection layer has been removed.
A specific area of the optical disc records physical character information that
shows the location and length of the concave pit or the pit string in the processed area.
