Modifying Units in DWG Workmode
When you open a DWG file in MicroStation, you should set the file's units on the DWG Open Options dialog. However, once the DWG file is open, you can modify the unit settings under the Design File Settings dialog, Working Units category. If you change the (Linear Units) Format setting, you must make sure that the Resolution (under Advanced Settings) is set to a consistent base unit. Specifically, when you change the Format to Engineering or Architectural, the Resolution must be inch-based in order to save the new unit format back to a DWG file.
CAUTION: Changing the Resolution can
change the size of existing geometry in the model; therefore, this is not the
recommended method for changing units in DWG files. Use this method only if you
know that the change in unit resolution will not affect existing geometry size,
or if the change is the intended behavior. The recommended method for setting
the DWG units is to select the proper units when opening the DWG file.