Thanks (Guru) Phill ;-),

That's exactly what I try to achieve. So some bits of the prop need to be smooth and other bits need to have sharp edges.

This is what I do:

I load the prop and click the Group editor. In the dropdown menu I see the groups I specified in Silo. I select one and click "Assign smoothing ID". A window pops up and I fill in a number (!!??) and click OK. Then the window disappears and nothing else happens. I've searched everywhere (including the manual) to find any references to the numbers I typed, to no luck. Am I missing something?

TA, N