a table indicative of convertible data forms for the files stored in the shared folder as illustrated in fig5 the file administrating part 205 checks whether the files stored in the shared folder have the convertible data forms fig5 is an exemplary structural view of a table including the convertible data forms the table illustrated in fig5 associates original data forms with convertible data forms which can be converted from the original data forms for example referring to fig5 the file whose original data form is u201c doc u201d is associated with the convertible data forms of u201c pdf ps rpcs jpg u201d therefore when the file administrating part 205 refers to the table illustrated in fig5 the file administrating part 205 can check the convertible data forms of u201c pdf ps rpcs jpg u201d which can be converted from the file having the data form of u201c doc u201d after the file administrating part 205 checks the convertible data forms for the files stored in the shared folder the file administrating part 205 creates the file information for files and folders stored in the shared folder as illustrated in fig6 fig6 is an exemplary structural view of the file information referring to fig6 the file information includes items of u201c file name u201d u201c file size u201d u201c folder identifying information u201d u201c convertible data form u201d u201c converted data form u201d u201c file created date u201d u201c file updated date u201d and u201c file finally accessed date u201d the item of u201c convertible data form.