Figure 8.

The classificatory parameter defined Phase is the Top View graphical representation of the 3D spatial evolution of the curve as reported in Figure 4. This parameter is obtained dividing the spinal area for the diagonal of the minimum rectangle in which the Top View is inscribable. This allows to verify mathematically how much is "open" the curve considered: the highest value is reached with a circle (anisophasic curve, according to our definition), the lowest with a line (isophasic curve, according to our definition).