Hi Mike,

You seem to have a good grasp of it.

>> don't understand fully how step 4 is achieved.
In particular, what does the MoveByVec node do? <<

The vectors (direction+magnitude) need to act upon something.
So the points of the major circle are converted to point objects
for vector transformation then converted back to a point array,
that then in turn defines the path of the curve.

Does that make sense?

James