1. A document management system comprising: a storage section that stores at least one of an electronic manuscript and an electronic document generated by combining a plurality of pages of electronic manuscripts; a reference electronic manuscript acquisition section that acquires a reference electronic manuscript used for identifying a specified reference page, among the pages of the electronic manuscripts, of an edit part in an edit electronic document that is an electronic document to be edited and is read from the storage section; an edit part identification section that identifies the specified reference page of the edit part in the edit electronic document based on the reference electronic manuscript; a document editing processing section that performs editing processing for the specified reference page of the edit part identified by the edit part identification section, in units of electronic manuscripts; and an edit electronic manuscript acquisition section that acquires a given number of sheets of electronic manuscripts necessary in the editing processing, wherein the editing processing includes one of a manuscript deletion mode, a manuscript substitution mode, a manuscript addition mode, and a manuscript exchange mode, wherein the edit part identification section identifies at least one of a start position of the editing processing, a start position of the edit part, and an end position of the edit part based on the electronic manuscript, which is located at the specified reference page and is extracted by an edit reference manuscript extraction section, and with adopting, as a reference, the start position of the editing processing, the start position of the edit part, or the end position of the edit part identified by the edit part identification section, the document editing processing section performs the editing processing for the electronic manuscripts in the edit part of the edit electronic document, and wherein the edit part identification section identifies at least one of a start position of substitution processing, a start position of a substitution range, and an end position of the substitution range based on the electronic manuscript, which is located at the specified reference page and is extracted by the edit reference manuscript extraction section, and the document editing processing section includes a substitution processing section that, with adopting as a reference the start position of substitution processing, the start position of substitution range, or the end position of substitution range identified by the edit part identification section, substitutes electronic manuscripts within the substitution range in the edit electronic document with the given number of sheets of the electronic manuscripts acquired by the edit electronic manuscript acquisition section.
4. The document management system according to claim 1 , wherein the edit part identification section compares the reference electronic manuscript against each of the electronic manuscripts constituting the edit electronic documents and identifies the edit part based on a score indicating a level of similarity between the reference electronic manuscript and each of the electronic manuscripts.