Patent ID: 8024381

Claim:
A file management method for managing a plurality of files containing content recorded on a recording medium, comprising the steps of: classifying different types of extract information, extracted from the content of different files, into plural different groups including a property group to which property information of the files is allocated and one or more different groups corresponding to said types of extract information, said property group of files and said different groups of files comprising an index file; allocating the extract information of one of the files to a plurality of slots in at least one of the different groups, each of said plurality of slots in said at least one group exhibiting fixed slot length; and allocating information describing the one file to a plurality of the fixed slot length slots in the property group so that said property group has slots corresponding to the slots of the at least one different group, wherein each of the slots of the property group has set therein management information for managing that slot of the property group and said management information also managing the corresponding slot of the at least one different group, wherein the management information of each of the slots of the property group has set therein a slot number for specifying the corresponding slot of the at least one different group and valid/invalid information, said valid information in a respective slot of the property group representing that the respective slot of the property group and the corresponding slot of the at least one different group are valid slots, wherein useful information is indicated as being stored in said valid slot of said at least one different group, and said invalid information in a respective slot of the property group representing that the respective slot of the property group and the corresponding slot of the at least one different group are invalid slots, thereby representing a free slot in said at least one different group in which useful information is not stored, and wherein the property group has a header containing a last valid slot number for identifying the slot number of the last slot of the property group that is set to valid, thereby identifying the slot number of the last slot of the property group and the last slot of the at least one different group in which useful information is stored, so that when searching the one file for content, the index file is not searched beyond the last slot of the property group that is identified by said slot number.