Extract isocurve from Sub D

Hi, I was wandering if there is a way rebuild and extract isocuves from subD. Now I am converting the shape to nurbs, rebuild the surface and than extract all horizontal isocurves.

Is it possible to do it directly on a subD surface ?

IsoCrv no, but edges _DupEdge,
to increase count of edges in combination with edge tools, ala _InsertEdge, _Subdivide, _Bridge…

right, the good thing of isocrv, is that if use rebuild i can define the number of isocrvs( edges) and will be spaced equally) sort of what subdivide does , thanks for replay