AutoCAD 2008 User's
Guide > Share Data Between
Drawings and Applications > Work with Data in
Other Formats > Import, Attach, or
Open Other File Formats > Attach DGN Files as
Underlays >
Attach and Detach DGN Underlays
You can add or remove DGN underlays within drawing files, or you can change their position, scale, and orientation.
You can attach DGN files as underlays to a drawing file.
DGN underlays can be detached from a drawing file.
