DGN - MicroStation Design File
This is a 2D/3D drawing format which is ued by the MicroStation construction design software package. It is based on either the V8 DGN standard format or the older Intergraph Standard File Format (ISFF). It may be converted to the universal DWG format with AutoCAD LDT. These files may be opened with the free Bentley View program or with the Bentley Systems Microstation program. The DGN file format also has support by many other third party applications and is short for 'design'.