Image Number 13 for United States Patent #8145580.
Data elements are classified into a plurality of folders in accordance with classification conditions on the basis of each of a plurality of metadata elements. Data elements in each of the folders are further classified into a plurality of folders on the basis of a metadata element different from the metadata element associated with the folder. This operation is repeated in accordance with the number of metadata elements to organize a folder system having a tree structure. When a classification result based on a given one of the metadata elements is present in only one folder in the organized folder system and is not present in other folders arranged in the same layer as that of the folder, the other folders are deleted.