Patent ID: 7092342

Claim:
An optical disc comprising: a sector including a plurality of frames which are classified into a first type and a second type, wherein: the first-type frames include a plurality of recording marks whose edges are at standard positions, and the second-type frames include a plurality of recording marks whose edges are displaced from standard positions; the displaced edges in the second-type frames are classified into leading edges that exist before standard positions, and lagging edges that exist after standard positions, the leading edges and the lagging edges being arranged in accordance with a predetermined rule; the length of each recording mark indicates the number of successive first channel bit values in main information recorded on said sector; an arrangement of the leading edges and the lagging edges indicates a first bit value of sub information that is superposed on the main information; the leading edges and the lagging edges cause jitters; and an edge displacement amount Δt is determined from σ′≧√{square root over (σ 2 +Δt 2 )}, where σ denotes a standard deviation of base jitters that occur naturally, and σ′ denotes a permissible jitter amount for said optical disc.