Thank you James.
Will study more tomorrow.

Most of the Object nodes have a Factory which handles Frames. So their examples only help partially.

"null" is used with Center input, for unspecified center. Each center frame comes from the pointarray inputs to Center.
var frame = center.getFrame();

Solids / polyhedron shows more about Frames.

infonodes by Karsten, (Infos/showFrame), shows how to add the frame to the x, y, z points of the curve factory,
which will need to be added to the two helper functions Polar2Cartesian() and eval_rho().
zValue input is no longer needed. z will come from the Center input.

- Brian