Spline

Splines are general smoothed curves defined using points in the 2D or 3D space. Three-dimensional splines do not generally have to lie in the same plane. However, if a spline is used to define a boundary of a surface, then all its definition points need to lie in this surface. A spline can be defined either graphically using a command on the Edit Bar or in the dialog where we select a particular type of spline:

There are three types of splines available: