The class Search_traits_2<Kernel> can be used as a template parameter of the kd tree and the search classes.
#include <CGAL/Search_traits_2.h>

 Number type. 

 Point type. 
 
 Iso box type.  

 Sphere type. 
 
 
An iterator over the Cartesian coordinates.  
 
 
A functor with two function operators, which return the begin and past the end iterator for the Cartesian coordinates. The functor for begin has as argument a Point_d. The functor for the past the end iterator, has as argument a Point_d and an int.  
 
 
Functor with operator to construct the iso box from two points.  
 
 Functor with operator to construct the center of an object of type Sphere_d.  
 
 
Functor with operator to compute the squared radius of a an object of type Sphere_d.  
 
 
Functor with operator to construct the vertex with lexicographically smallest coordinates of an object of type Iso_box_d.  
 
 
Functor with operator to construct the vertex with lexicographically largest coordinates of an object of type Iso_box_d. 
Search_traits_3<Kernel>
Search_traits<NT_,Point,CartesianConstIterator,ConstructCartesianConstIterator