""""""""""find the point on a curve that has a specific perpendicular direction" cannot be solved by just doing a rotation of a construction line - it involves some kind of snap function that will seek through the curve finding the right spot on the curve that has the curve tangent or curve perpendicular going in that particular direction.""""""""""

Yes, the rotation was just an example of using the kept cline as an object. It seemed the question was "moving an existing cline from somewhere else" perp to perp on a curve somewhere else, which can be solved by the keep c-line/object transform thing I showed. I was just pushing to see if I could get the keep c-line beefed up, because what you are showing is "just make a new c-line" which works fine.

Kindof like asking to have the BoundingBox command have an axis directional method added. I think that kind of tinkering just needs to wait, because it can be acheived by rotating the part, instead of making the command do the rotation.