The Design.dgnlib is the level library belonging to
the Office of Design.  It contains three basic
divisions, which are:

dsn* - General Road Design levels, including Methods

pho* - Photogrammetry levels

sol* - Soils Design levels

The Design.dgnlib is one of many level libraries used
by the Iowa DOT.  Other office level libraries can be
obtained by visiting their specific office web sites.