To add a reparameterization curve to a surface, the surface must contain more than one curve in a given direction, as in a loft surface or a boundary surface. You can add any number of reparameterization curves in the U direction and in the V direction. The use of reparameterization curves is limited in the following cases:

Make sure that reparameterization curves in the same direction do not cross each other or any internal curves. The rules for dragging internal curves apply to dragging reparameterization curves.