| 摘要 |
PURPOSE: An optical recording medium is provided to prevent an authorized recording/reproduction and an illegal copy of an information data in the optical recording medium. CONSTITUTION: At least a portion of groove tracks in a information-data recording region of an optical recording medium comprises a plurality of groove portions(12) separated by groove-absent portions(13) in a rotational direction of the optical recording medium, each of the mark portions or each of the space portions includes one of the groove-absent portions. At least one of two groove tracks adjacent to prepit train, which is formed in land tracks, has a continuous groove portion(12A,12B) or a groove-absent portion extending at least from a leading end to a trailing end of at least one prepit included in the prepit train in a rotational direction of the optical recording medium. The frequency band for separation of the groove tracks includes at least a portion of a frequency band of a modulated recording signal for recording information data on the optical recording medium.
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