> There is no single answer. Exactly how its coded up depends on the command and the type of edge involved. In general I would treat the specification of curvature continuity as a suggestion or goal that is command tries it’s best to achieve, as opposed to a guarantee of results.
> However, mathematically curvature continuous means the sectional curvature agrees all directions. Equivalently, if the principle curvatures agree and the principle curvature directions agree then the surfaces are curvature continuous.
> For example, a plane meeting a cylinder (like a fillet on a box) is not curvature continuous even though the minimum curvature is 0 on both surfaces. Similarly a spherical end cap on a cylinder is not curvature continuous even though the max curvatures agree. In fact both the min and the max could agree but be achieved in different directions in which case the surfaces are still not curvature continuous.
Quindi: Tolleranza assoluta e angolare.