Data in DWG files can be attached to the open file as references or cells. When you attach a DWG file as a reference, you can set options for units on the DWG Open Options dialog. To do this, open the Attach Reference dialog and click the Options button. Generally, you will get good results if you set both Units options to Design Center Units. If the system variable INSUNITS is appropriately set in AutoCAD, MicroStation can automatically interpret the DWG units.

When you insert a DWG file as a cell, the units settings are controlled by the DWG Open Options dialog (File > Open, then click the DWG Options button). Again, it is generally best to set the Units options to Design Center Units.