Information management method, data recording medium, data recording method, information retrieving method and information retrieving apparatus

Object of the present invention is to be able to access quickly. The optical disc data track is divided into a volume management area and the extension area, the data file is recorded in the extension area, directory management information and file management information recorded in the volume management area. Volume management area consists of 16 groups. Data volume management area allocation unit of 2K bytes, allocation unit of extents is 4K bytes.