The controls in this area determine advanced aspects of the conversion

When selected, NURBS curves whose description does not correspond with the description in think3 are split into several separate NURBS.

The controls in this area determine general aspects of the conversion of entities into NURBS

When selected, specialized curves and surfaces are converted into NURBS and their conversion is controlled by the Tolerance value.

When selected, polyline entities are converted to NURBS; when not selected, each polyline entity is converted into a set of component segments.

Determines the tolerance value used to convert NURBS during conversion of the file.