According to the COLLADA spec, the file would contain two tangents per segment for a Hermite spline or two control points per segment for a Bezier spline. In the spec, they are called "in" and "out" tangents for both the tangents of the Hermite curve and the control points of the Bezier curve.

If the curves are C<sup>2</sup>, we could compute them, but not for anything less. How does Modo compute them?

I'll look into converting to other spline types.