Lead In And Lead Out Lengths
Cycles: Parallel Plane, Z Level, Profile, Spiral, Equidistant, Pocket Morphing, Contour Morphing, Auto // Plane, Auto Equidistant, Auto Z Level, Vertical // Plane, Vertical Equidistant, Vertical Z Level, Horizontal // Plane, Horizontal Equidistant, Facing (Shape), Finishing, Finish Reworking (Shape), 3X Isoparametric, 5X Isoparametric, Plunge Contouring
Definition
Tool positioning when leading and retracting.
Lead in and lead out lengths
These lengths depend on the strategy used. If tangent is chosen this "length" is in fact a radius.

Look at the image above:
The lead in is Normal with a 5 mm lead in length.
The lead out is Tangent with a 2 mm lead out length (a radius).