CGAL 5.1.1  2D Triangulation

#include <CGAL/Constrained_triangulation_2.h>
Intersection tag for constrained triangulations, when input constraints are not allowed to intersect except if the intersection does not require any new point construction.
This for example allows configurations such as two segments intersecting in a 'T', or overlapping (and even identical) segments.
This is the default tag.