1. A data structure having a data area and its management area, wherein data is stored in said data area in a form of one or more objects, each said object includes one or more data units, said data unit includes record information in a form of one or more packs, said record information being presented within a prescribed period of time, said management area includes management information for managing said objects, said management information includes program chain information for specifying an order of presentation of said objects, and said program chain information includes one or more pieces of cell information, and wherein said cell information has an area for describing information of one or more entry points, each said entry point indicating a position to enter said record information.