Group objects in layers during STEP export

I’m currently trying to export my geometry to Pointwise. This means that the way both software packages read data from the STEP becomes important. Rhino imports layer information from STEP files by layer description, while Pointwise imports layer information by layer number.

STEP files dump each separate geometry into it’s “own” layer. For example, if I have a Farfield layer with four surfaces in it the STEP file creates four separate layer assignments called Farfield. If I join them into one polysurface I get just one layer assignment. However, for some of my geometry’s I need more than one object per layer. Grouping objects in Rhino does not resolve the problem. This is how STEP deals with layer assignments:

#191=PRESENTATION_LAYER_ASSIGNMENT('FarField','',(#212));
#192=PRESENTATION_LAYER_ASSIGNMENT('DuctsTEFillet','',(#213));
#193=PRESENTATION_LAYER_ASSIGNMENT('Ducts','',(#214));
#194=PRESENTATION_LAYER_ASSIGNMENT('Ducts','',(#215));
#195=PRESENTATION_LAYER_ASSIGNMENT('DuctsTEFillet','',(#216));
#196=PRESENTATION_LAYER_ASSIGNMENT('DuctsTEFillet','',(#217));
#197=PRESENTATION_LAYER_ASSIGNMENT('Ducts','',(#218));
#198=PRESENTATION_LAYER_ASSIGNMENT('Ducts','',(#219));
#199=PRESENTATION_LAYER_ASSIGNMENT('Ducts','',(#220));
#200=PRESENTATION_LAYER_ASSIGNMENT('Ducts','',(#221));
#201=PRESENTATION_LAYER_ASSIGNMENT('Ducts','',(#222));
#202=PRESENTATION_LAYER_ASSIGNMENT('Airfoil','',(#223));
#203=PRESENTATION_LAYER_ASSIGNMENT('Airfoil','',(#224));
#204=PRESENTATION_LAYER_ASSIGNMENT('AirfoilTE','',(#225));
#205=PRESENTATION_LAYER_ASSIGNMENT('Airfoil','',(#226));
#206=PRESENTATION_LAYER_ASSIGNMENT('Airfoil','',(#227));
#207=PRESENTATION_LAYER_ASSIGNMENT('AirfoilTE','',(#228));
#208=PRESENTATION_LAYER_ASSIGNMENT('Airfoil','',(#229));
#209=PRESENTATION_LAYER_ASSIGNMENT('Airfoil','',(#230));
#210=PRESENTATION_LAYER_ASSIGNMENT('RotIn','',(#231));
#211=PRESENTATION_LAYER_ASSIGNMENT('RotIn','',(#232));

So the problem is that Rhino does too good a job :wink: . My question: Is there a way for me to group objects in a layer in such a way that the STEP import does not create duplicate layer assignments? I’m currently also talking to Pointwise.