CGAL 5.1  2D Triangulation

#include <CGAL/Triangulation_face_base_2.h>
Fb.
The class Triangulation_face_base_2
is a model for the concept TriangulationFaceBase_2
.
It is the default face base class for basic and Delaunay triangulation.
These default base class can be used directly or can serve as a base to derive other base classes with some additional attribute (a color for example) tuned for specific applications.
Traits  must be a geometric traits class. The geometric traits is actually not used by the class. 
Fb  has to be a model of the concept TriangulationDSFaceBase_2 and will serve as a base class for Triangulation_face_base_2 . CGAL provides a default instantiation for this parameter which is Triangulation_ds_face_base_2<> . 
CGAL::Triangulation_ds_face_base_2<Tds>
CGAL::Triangulation_vertex_base_2<Traits,Vb>
CGAL::Triangulation_2<Traits,Tds>