Lets you select an animation layer where you want to add the point on poly constraint. See Create point on poly constraints for more information.

Determines whether the point on poly constraint is restricted to a specific axis (X, Y, Z) or to All axes.

Specifies how much the constrained object’s position can be influenced by the mesh. Use the slider to select values from 0.0000 to 10.0000. Default is 1.0000.