12. The computer system as claimed in claim 11 , wherein the document managing apparatus is located in a Web site on a Web or, on an Intranet to which the client apparatus is coupled or, both in the Web site and on the Intranet.
11. An computer system comprising a document managing apparatus configured to manage a set of electronic documents and a client apparatus configured to display the electronic document, wherein the client apparatus comprises: a computer processor comprising: a selection accepting part configured to accept a first character string from characters or a character string in a reading or inspecting document that is displayed; an index information acquiring part configured to acquire a second character string to be used as index information for searching the reading or inspecting document, based on identification information of the reading or inspecting document, and to delete the second character string that overlaps with the first character string from the index information; and a search control part configured to request the document managing apparatus to execute a search based on the first character string and the second character string as search keywords, wherein the index information acquiring part extracts each word having an occurrence that is greater than a predetermined value from the index information as the second character string, and wherein: the index information acquiring part extracts at least one of the words having a co-occurrence that is greater than the predetermined value with respect to the first character string from a plurality of second character strings based on a co-occurrence management table that manages the co-occurrence for each combination of words in the index information as a third character string, and the search control part executes the search based on the first character string and the third character string.