BezierTo() Method

I've been doing a little exploration in the area of Fuse development, and in all of the shape-based fuses I've seen so far, nobody has used BezierTo(). After poking around in the SDK trying to get a handle on how it might work, I have been almost completely stymied. It appears to take six arguments:
BezierTo(Handle X, Handle Y, unknown, End Point X, unknown, End Point Y)
Those two unknown parameters do not seem to create any visible changes. I assume they might be intended to be the location of the incoming handle for the end point. Based on my exploration of the method, I am tempted to suspect that its implementation is incomplete.
Does anyone know anything more about this topic? Is there any word on the "dedicated Fuses documentation and reference" (Fusion 8 Scripting Guide page 29)?
BezierTo(Handle X, Handle Y, unknown, End Point X, unknown, End Point Y)
Those two unknown parameters do not seem to create any visible changes. I assume they might be intended to be the location of the incoming handle for the end point. Based on my exploration of the method, I am tempted to suspect that its implementation is incomplete.
Does anyone know anything more about this topic? Is there any word on the "dedicated Fuses documentation and reference" (Fusion 8 Scripting Guide page 29)?