The class Level_interval<FaceHandle> represents intervals for the minimum and maximum value of the zcoordinate of a face of a triangulation.
#include <CGAL/Level_interval.h>

 The type of the $$zcoordinate of points stored in vertices of faces. 
 
Default constructor.
 
 
Constructs the interval with smallest and largest z coordinate of the points
stored in the vertices of the face fh points to.


 returns the face handle. 


Inserts the interval i into the stream os.
