This invention allows the user to insert an entry point (bookmark) at an
arbitrary recording position of video data, audio data, and the like as
if he or she placed a bookmark between pages of a book. Information
RTR_VMG that manages recorded objects includes movie cell entry point
information M_C_EPI. M_C_EPI includes entry point playback time
information EP_PTM and text information PRM_TXTI that pertains to an
entry point. PRM_TXTI can store text information that pertains to its
contents together with type information and date information of an entry
point.