Loft component inside magic hint

Hi!

I'm creating an application that has to work (to some degree) similarly to GH definition provided by artist. It's a webGL stuff. It all revolves around NURBS surfaces. We are experiencing quite visible differences between GH output and our custom application using the same input curves for surface (and hopefully the same surface settings).

Input curves are 4 bsplines, deg3, 7 control points. I'm creating NURBS (uniform weights), which generates 4x7 control points surface. It looks similar to GH, yet after close inspection it looks like Loft component used by artist generates NURBS with 6x7 control points (given those same 4 input curves). Basically there are 2 ghost curves added close to the edges (please see the attached image).

This of course alters the way surface looks when comparing to 4x7 surface... What is the logic behind those points? How can I create them manually in my code in separate application to get the same surface (or can I avoid their creation)?

We've tried adding more input curves (6) to cover the low number of control points in vertical direction, but Loft still has n+2 vertical points...

Any insight, help greatly appreciated!

Regards,

Boris Zapotocky