DGN (design) is the name used for CAD file formats supported by Bentley Systems` MicroStation and Intergraph`s Interactive Graphics Design System (IGDS) CAD programs. There are two versions of DGN: The DGN format is used in many large projects, including buildings, highways, bridges, process plants, shipbuilding. DGN is a competing format to Aut..... Found on http://en.wikipedia.org/wiki/DGN