diff --git a/Cartesian_kernel/include/CGAL/Cartesian/Point_3.h b/Cartesian_kernel/include/CGAL/Cartesian/Point_3.h
index 8ef92f656f0..ba2b80bb690 100644
--- a/Cartesian_kernel/include/CGAL/Cartesian/Point_3.h
+++ b/Cartesian_kernel/include/CGAL/Cartesian/Point_3.h
@@ -172,52 +172,6 @@ PointC3<R>::bbox() const
   return Bbox_3(xp.first, yp.first, zp.first, xp.second, yp.second, zp.second);
 }
 
-#ifndef CGAL_CARTESIAN_NO_OSTREAM_INSERT_POINTC3
-template < class R >
-std::ostream &
-operator<<(std::ostream &os, const PointC3<R> &p)
-{
-    switch(os.iword(IO::mode)) {
-    case IO::ASCII :
-        return os << p.x() << ' ' << p.y()  << ' ' << p.z();
-    case IO::BINARY :
-        write(os, p.x());
-        write(os, p.y());
-        write(os, p.z());
-        return os;
-    default:
-        os << "PointC3(" << p.x() << ", " << p.y()  << ", " << p.z() << ")";
-        return os;
-    }
-}
-#endif // CGAL_CARTESIAN_NO_OSTREAM_INSERT_POINTC3
-
-#ifndef CGAL_CARTESIAN_NO_ISTREAM_EXTRACT_POINTC3
-template < class R >
-std::istream &
-operator>>(std::istream &is, PointC3<R> &p)
-{
-    typename R::FT x, y, z;
-    switch(is.iword(IO::mode)) {
-    case IO::ASCII :
-        is >> x >> y >> z;
-        break;
-    case IO::BINARY :
-        read(is, x);
-        read(is, y);
-        read(is, z);
-        break;
-    default:
-        std::cerr << "" << std::endl;
-        std::cerr << "Stream must be in ascii or binary mode" << std::endl;
-        break;
-    }
-    if (is)
-	p = PointC3<R>(x, y, z);
-    return is;
-}
-#endif // CGAL_CARTESIAN_NO_ISTREAM_EXTRACT_POINTC3
-
 CGAL_END_NAMESPACE
 
 #endif // CGAL_CARTESIAN_POINT_3_H
diff --git a/Homogeneous_kernel/include/CGAL/Homogeneous/PointH2.h b/Homogeneous_kernel/include/CGAL/Homogeneous/PointH2.h
index 45a11217161..3ff8f428a44 100644
--- a/Homogeneous_kernel/include/CGAL/Homogeneous/PointH2.h
+++ b/Homogeneous_kernel/include/CGAL/Homogeneous/PointH2.h
@@ -17,7 +17,7 @@
 //
 // $URL$
 // $Id$
-// 
+//
 //
 // Author(s)     : Stefan Schirra
 
@@ -53,7 +53,7 @@ public:
 
     PointH2() {}
 
-    PointH2(const Origin &)  
+    PointH2(const Origin &)
        : base (RT(0), RT(0), RT(1)) {}
 
     PointH2(const RT& hx, const RT& hy )
@@ -81,12 +81,12 @@ public:
     FT      operator[](int i)  const;
     const RT & homogeneous(int i) const;
 
-    Cartesian_const_iterator cartesian_begin() const 
+    Cartesian_const_iterator cartesian_begin() const
     {
       return Cartesian_const_iterator(static_cast<const Point_2*>(this), 0);
     }
 
-    Cartesian_const_iterator cartesian_end() const 
+    Cartesian_const_iterator cartesian_end() const
     {
       return Cartesian_const_iterator(static_cast<const Point_2*>(this), 2);
     }
@@ -101,7 +101,7 @@ CGAL_KERNEL_INLINE
 bool
 PointH2<R>::operator==( const PointH2<R>& p) const
 { // FIXME : Predicate
-  return (  (hx() * p.hw() == p.hx() * hw() ) 
+  return (  (hx() * p.hw() == p.hx() * hw() )
           &&(hy() * p.hw() == p.hy() * hw() ) );
 }
 
diff --git a/Homogeneous_kernel/include/CGAL/Homogeneous/PointH3.h b/Homogeneous_kernel/include/CGAL/Homogeneous/PointH3.h
index 173478412e7..5c06ad81603 100644
--- a/Homogeneous_kernel/include/CGAL/Homogeneous/PointH3.h
+++ b/Homogeneous_kernel/include/CGAL/Homogeneous/PointH3.h
@@ -17,7 +17,7 @@
 //
 // $URL$
 // $Id$
-// 
+//
 //
 // Author(s)     : Stefan Schirra
 
@@ -78,12 +78,12 @@ public:
   FT    operator[](int i) const;
 
 
-  Cartesian_const_iterator cartesian_begin() const 
+  Cartesian_const_iterator cartesian_begin() const
   {
     return Cartesian_const_iterator(static_cast<const Point_3*>(this), 0);
   }
 
-  Cartesian_const_iterator cartesian_end() const 
+  Cartesian_const_iterator cartesian_end() const
   {
     return Cartesian_const_iterator(static_cast<const Point_3*>(this), 3);
   }
@@ -204,53 +204,6 @@ bool
 PointH3<R>::operator!=( const PointH3<R> & p) const
 { return !(*this == p); }
 
-#ifndef CGAL_NO_OSTREAM_INSERT_POINTH3
-template < class R >
-std::ostream &operator<<(std::ostream &os, const PointH3<R> &p)
-{
-    switch(os.iword(IO::mode)) {
-    case IO::ASCII :
-        return os << p.hx() << ' ' << p.hy() << ' ' << p.hz() << ' ' << p.hw();
-    case IO::BINARY :
-        write(os, p.hx());
-        write(os, p.hy());
-        write(os, p.hz());
-        write(os, p.hw());
-        return os;
-    default:
-        return os << "PointH3(" << p.hx() << ", "
-                                << p.hy() << ", "
-                                << p.hz() << ", "
-                                << p.hw() << ')';
-    }
-}
-#endif // CGAL_NO_OSTREAM_INSERT_POINTH3
-
-#ifndef CGAL_NO_ISTREAM_EXTRACT_POINTH3
-template < class R >
-std::istream &operator>>(std::istream &is, PointH3<R> &p)
-{
-  typename R::RT hx, hy, hz, hw;
-  switch(is.iword(IO::mode)) {
-  case IO::ASCII :
-        is >> hx >> hy >> hz >> hw;
-        break;
-  case IO::BINARY :
-        read(is, hx);
-        read(is, hy);
-        read(is, hz);
-        read(is, hw);
-        break;
-  default:
-        std::cerr << "" << std::endl;
-        std::cerr << "Stream must be in ascii or binary mode" << std::endl;
-        break;
-  }
-  p = PointH3<R>(hx, hy, hz, hw);
-  return is;
-}
-#endif // CGAL_NO_ISTREAM_EXTRACT_POINTH3
-
 
 template < class R >
 inline
diff --git a/Kernel_23/include/CGAL/Point_3.h b/Kernel_23/include/CGAL/Point_3.h
index 780548ff562..6d6f1b616d6 100644
--- a/Kernel_23/include/CGAL/Point_3.h
+++ b/Kernel_23/include/CGAL/Point_3.h
@@ -25,6 +25,7 @@
 #define CGAL_POINT_3_H
 
 #include <CGAL/Origin.h>
+#include <CGAL/representation_tags.h>
 
 CGAL_BEGIN_NAMESPACE
 
@@ -166,22 +167,115 @@ bool
 operator!=(const Origin& o, const Point_3<R>& p)
 { return p != o; }
 
-#if 0 //ndef CGAL_NO_OSTREAM_INSERT_POINT_3
+
+#ifndef CGAL_NO_OSTREAM_INSERT_POINT_3
+
+template <class R >
+std::ostream&
+insert(std::ostream& os, const Point_3<R>& p,const Cartesian_tag&) 
+{
+    switch(os.iword(IO::mode)) {
+    case IO::ASCII :
+        return os << p.x() << ' ' << p.y() << ' ' << p.z();
+    case IO::BINARY :
+        write(os, p.x());
+        write(os, p.y());
+        write(os, p.z());
+        return os;
+    default:
+        return os << "PointC3(" << p.x() << ", " << p.y()
+                                         << ", " << p.z() << ')';
+    }
+}
+
+template <class R >
+std::ostream&
+insert(std::ostream& os, const Point_3<R>& p,const Homogeneous_tag&)
+{
+  switch(os.iword(IO::mode))
+  {
+    case IO::ASCII :
+        return os << p.hx() << ' ' << p.hy() << ' ' << p.hz() << ' ' << p.hw();
+    case IO::BINARY :
+        write(os, p.hx());
+        write(os, p.hy());
+        write(os, p.hz());
+        write(os, p.hw());
+        return os;
+    default:
+        return os << "PointH3(" << p.hx() << ", "
+                                << p.hy() << ", "
+                                << p.hz() << ", "
+                                << p.hw() << ')';
+  }
+}
+
 template < class R >
 std::ostream&
 operator<<(std::ostream& os, const Point_3<R>& p)
 {
-  typedef typename  R::Kernel_base::Point_3  Rep;
-  return os << static_cast<const Rep&>(p);
+  return insert(os, p, typename R::Kernel_tag() );
 }
+
 #endif // CGAL_NO_OSTREAM_INSERT_POINT_3
 
-#if 0 //ndef CGAL_NO_ISTREAM_EXTRACT_POINT_3
-template < class R >
-std::istream& operator>>(std::istream& is, Point_3<R>& p)
+#ifndef CGAL_NO_ISTREAM_EXTRACT_POINT_3
+
+template <class R >
+std::istream&
+extract(std::istream& is, Point_3<R>& p, const Cartesian_tag&) 
 {
-  typedef typename  R::Kernel_base::Point_3  Rep;
-  return is >> static_cast<Rep&>(p);
+    typename R::FT x, y, z;
+    switch(is.iword(IO::mode)) {
+    case IO::ASCII :
+        is >> x >> y >> z;
+        break;
+    case IO::BINARY :
+        read(is, x);
+        read(is, y);
+        read(is, z);
+        break;
+    default:
+        std::cerr << "" << std::endl;
+        std::cerr << "Stream must be in ascii or binary mode" << std::endl;
+        break;
+    }
+    if (is)
+	p = Point_3<R>(x, y, z);
+    return is;
+}
+
+
+template <class R >
+std::istream&
+extract(std::istream& is, Point_3<R>& p, const Homogeneous_tag&) 
+{
+  typename R::RT hx, hy, hz, hw;
+  switch(is.iword(IO::mode))
+  {
+    case IO::ASCII :
+        is >> hx >> hy >> hz >> hw;
+        break;
+    case IO::BINARY :
+        read(is, hx);
+        read(is, hy);
+        read(is, hz);
+        read(is, hw);
+        break;
+    default:
+        std::cerr << "" << std::endl;
+        std::cerr << "Stream must be in ascii or binary mode" << std::endl;
+        break;
+  }
+  p = Point_3<R>(hx, hy, hz, hw);
+  return is;
+}
+
+template < class R >
+std::istream&
+operator>>(std::istream& is, Point_3<R>& p)
+{
+  return extract(is, p, typename R::Kernel_tag() );
 }
 #endif // CGAL_NO_ISTREAM_EXTRACT_POINT_3
 
diff --git a/Kernel_23/include/CGAL/Sphere_3.h b/Kernel_23/include/CGAL/Sphere_3.h
index aaafe9b3a4e..10572f8ba93 100644
--- a/Kernel_23/include/CGAL/Sphere_3.h
+++ b/Kernel_23/include/CGAL/Sphere_3.h
@@ -153,7 +153,6 @@ public:
     //return CGAL_NTS is_zero(squared_radius());
   }
 
-
 };
 
 template <class R_>