#Spline

Key N. A smooth curve through points: click the knots, a double click finishes it.

#Careful with definition

A spline is the freest entity in a sketch: every knot has two degrees of freedom, and defining it completely with dimensions is next to impossible. That is fine for a shaped surface and bad for a critical outline.

The rule is simple: where the shape is set by a function (a fairing, aerodynamics, ergonomics) a spline belongs; where it is set by a size (a fit, a hole, a joint) lines and arcs are better.

#A hint

Pin the spline ends to their neighbours with coincidence, otherwise the outline will come apart at the joint on the first change.