Moi flipping polygons on export.

 From:  Michael Gibson
4531.5 In reply to 4531.1 
Hi Andy - if your objects are not a closed solid then it is pretty much arbitrary which side happens to be the positive normal direction. It will vary depending on things like if you drew one of the original generator curves in a clockwise or counter-clockwise direction.

It's usually best to just use double-sided lighting in your rendering program so that you don't have to worry about which side of an open surface happens to be the positive surface normal direction.

You can use the Flip command in MoI to flip an open surface so that its positive normal will be pointing in the opposite direction too though:
http://moi3d.com/2.0/docs/moi_command_reference10.htm#flip

After you run the Flip command the objects that were flipped will generate a mesh with opposite normals from before.

- Michael