There should be some "series" of examples, where the intersection gradually go from
being transversal, to being degenerate, to disappear, or change topology.

The testbench should cover intersections with the following properties:
- transversal cases
- periodic surfaces
- surfaces that are only C1-continuous (quadratic splines)
- surfaces involving degenerate points (like the sphere)
- punctual intersections
- intersection curves
- partial coincidence areas
- isoparametric intersection curves
- higher order intersection points
- self intersections
- intersections at border of domain
- two free-form surfaces that "almost" meet
- intersecting spheres
- branch points
- an intersection with complex topology (net of intersection curves)
- nonintersecting but close surfaces
- intersections involving rational surfaces
- surfaces that intersect far from 0, so that the problem of double arithmetic
  becomes apparent


----------
What can be the useful "meta-data" to associate with examples?

* self-intersecting
* transversal
* periodic
* rational
* less than C2
* degenerate points

* 0-manifold intersections (point)
* 1-manifold intersections (curve)
* 2-manifold intersections (surface, PAC)

* contains branch intersection points
* contains higher-order intersection points
* contains tangential intersection curves

* isoparametric intersection curves
* intersection along border
* interior intersection loops

* non-intersecting

