How can I define the default units?

 From:  Jesse
229.5 In reply to 229.4 
Hi Michael,

There is probably an obvious answer to this, but if the units aren't defined,
why are they consistent with millimeters and come in with no unit conversion messages popping up,
when I bring a MoI model into Rhino? I've imported models from AutoCAD and other SW's
which were way out of scale.

-Jesse