Is this a drawing you're exporting from WF? Splines and Curves should come across in the part translation.
Below is a cut out of an article on modeler tolerances
If the gaps between edges and faces become too large, solid-modeling programs can become confused about the boundaries of the model. The system can no longer distinguish the inside of a part from the universe around it. In such cases, the user might receive a message that the model is "corrupted." Consequently, all systems employ a strategy for computing the maximum allowable gap, or "tolerance zone," between an edge and the two faces it bounds. Unfortunately, different systems employ different strategies for computing this tolerance.
Pro/Engineer employs a variable tolerance model. The maximum gap is a fraction of the total model size. So for large models, such as jet engines, Pro/E allows larger gaps, while for small models, such as watch parts, only small gaps are permitted. The relative tolerance model is a clever one, and it enables Pro/E to run fast. Unfortunately, no other major CAD firms have adopted this strategy.
The Parasolid kernel employed by Unigraphics, SolidWorks, Solid Edge, and Microstation employs a concept called "tolerant modeling." The tolerance is fixed, but larger gaps may be permitted on a face-by-face basis.
The difference in tolerance strategies causes problems when translating geometry from one system to another. Models coming from Pro/Engineer or Unigraphics may have gaps that aren't acceptable to CATIA or SolidDesigner. The reverse is also true: Models from fixed tolerance systems may be unacceptable to Pro/E or UG if they contain gaps that are too large.
Best Regards,
Heckler
Sr. Mechanical Engineer
SW2005 SP 5.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NVIDIA Quadro FX 1400
o
_`\(,_
(_)/ (_)
Never argue with an idiot. They'll bring you down to their level and beat you with experience every time.