A header analyzing unit extracts a header area and each table unit area in each of an old and a new executable files, and calls a difference extracting unit for each area. A segment data associating unit associates a segment data in the old executable file with a corresponding segment data...http://www.google.com.hk/patents/US5752039?utm_source=gb-gplus-share專利 US5752039 - Executable file difference extraction/update system and executable file difference extraction method 
