diff --git a/Old_Packages/CLN/TODO b/Old_Packages/CLN/TODO
index e9f2ba23df3..fe4f80e4d5f 100644
--- a/Old_Packages/CLN/TODO
+++ b/Old_Packages/CLN/TODO
@@ -1,7 +1,5 @@
 TODO:
 ----
-- Use a common include files, with a macro specifying the type ?
-  Maybe too dirty to live...
 - Add min/max wrappers depending on what is decided for CGAL.
 - Should I provide operator/(cl_I, cl_I) ?  Not sure.
 - Is it possible to factorize more code (to_double()...) ?
diff --git a/Old_Packages/CLN/changes.txt b/Old_Packages/CLN/changes.txt
index 99e4fd8ef9c..d1707b516a1 100644
--- a/Old_Packages/CLN/changes.txt
+++ b/Old_Packages/CLN/changes.txt
@@ -3,7 +3,8 @@ Changes done to the CLN package.
 Version 1.8 on ?? ?? 2000.
 - New maintainer file.
 - Removed old workaround for operator>>(Quotient<cl_I>).
-  So CLN version >= 1.0.2 is required now.
+  CLN version >= 1.0.2 is required now.
+- Namespace NTS introduction.
 
 Version 1.7 on 27 October 1999.
 - Added IO include files by default.
diff --git a/Old_Packages/CLN/include/CGAL/CLN/cl_complex.h b/Old_Packages/CLN/include/CGAL/CLN/cl_complex.h
index 3c7efa449cb..c5a63dff5eb 100644
--- a/Old_Packages/CLN/include/CGAL/CLN/cl_complex.h
+++ b/Old_Packages/CLN/include/CGAL/CLN/cl_complex.h
@@ -35,6 +35,7 @@ CGAL_BEGIN_NAMESPACE
 inline double	to_double	(const cl_N &I) { return cl_double_approx(I); }
 
 // Specialized utilities.
+namespace NTS {
 
 inline bool is_negative		(const cl_N &I) { return minusp(I); } 
 inline bool is_positive		(const cl_N &I) { return plusp(I); }
@@ -42,6 +43,8 @@ inline bool is_zero		(const cl_N &I) { return zerop(I); }
 inline Comparison_result compare (const cl_N &I, const cl_N &J)
 { return Comparison_result(cl_compare(I,J)); }
 
+} // namespace NTS
+
 CGAL_END_NAMESPACE
 
 // #ifdef CGAL_INTERVAL_ARITHMETIC_H
diff --git a/Old_Packages/CLN/include/CGAL/CLN/cl_dfloat.h b/Old_Packages/CLN/include/CGAL/CLN/cl_dfloat.h
index 9d2cf484dcd..3b8adc95171 100644
--- a/Old_Packages/CLN/include/CGAL/CLN/cl_dfloat.h
+++ b/Old_Packages/CLN/include/CGAL/CLN/cl_dfloat.h
@@ -35,6 +35,7 @@ CGAL_BEGIN_NAMESPACE
 inline double	to_double	(const cl_DF &I) { return cl_double_approx(I); }
 
 // Specialized utilities.
+namespace NTS {
 
 inline bool is_negative		(const cl_DF &I) { return minusp(I); } 
 inline bool is_positive		(const cl_DF &I) { return plusp(I); }
@@ -42,6 +43,8 @@ inline bool is_zero		(const cl_DF &I) { return zerop(I); }
 inline Comparison_result compare (const cl_DF &I, const cl_DF &J)
 { return Comparison_result(cl_compare(I,J)); }
 
+} // namespace NTS
+
 CGAL_END_NAMESPACE
 
 // #ifdef CGAL_INTERVAL_ARITHMETIC_H
diff --git a/Old_Packages/CLN/include/CGAL/CLN/cl_ffloat.h b/Old_Packages/CLN/include/CGAL/CLN/cl_ffloat.h
index 38b04119327..8975069bcc0 100644
--- a/Old_Packages/CLN/include/CGAL/CLN/cl_ffloat.h
+++ b/Old_Packages/CLN/include/CGAL/CLN/cl_ffloat.h
@@ -36,12 +36,16 @@ inline double	to_double	(const cl_FF &I) { return cl_double_approx(I); }
 
 // Specialized utilities.
 
+namespace NTS {
+
 inline bool is_negative		(const cl_FF &I) { return minusp(I); } 
 inline bool is_positive		(const cl_FF &I) { return plusp(I); }
 inline bool is_zero		(const cl_FF &I) { return zerop(I); }
 inline Comparison_result compare (const cl_FF &I, const cl_FF &J)
 { return Comparison_result(cl_compare(I,J)); }
 
+} // namespace NTS
+
 CGAL_END_NAMESPACE
 
 // #ifdef CGAL_INTERVAL_ARITHMETIC_H
diff --git a/Old_Packages/CLN/include/CGAL/CLN/cl_float.h b/Old_Packages/CLN/include/CGAL/CLN/cl_float.h
index 92b64d748e4..a5bccae97f5 100644
--- a/Old_Packages/CLN/include/CGAL/CLN/cl_float.h
+++ b/Old_Packages/CLN/include/CGAL/CLN/cl_float.h
@@ -36,12 +36,16 @@ inline double	to_double	(const cl_F &I) { return cl_double_approx(I); }
 
 // Specialized utilities.
 
+namespace NTS {
+
 inline bool is_negative		(const cl_F &I) { return minusp(I); } 
 inline bool is_positive		(const cl_F &I) { return plusp(I); }
 inline bool is_zero		(const cl_F &I) { return zerop(I); }
 inline Comparison_result compare (const cl_F &I, const cl_F &J)
 { return Comparison_result(cl_compare(I,J)); }
 
+} // namespace NTS
+
 CGAL_END_NAMESPACE
 
 // #ifdef CGAL_INTERVAL_ARITHMETIC_H
diff --git a/Old_Packages/CLN/include/CGAL/CLN/cl_integer.h b/Old_Packages/CLN/include/CGAL/CLN/cl_integer.h
index 352f9f8774a..236e2949d18 100644
--- a/Old_Packages/CLN/include/CGAL/CLN/cl_integer.h
+++ b/Old_Packages/CLN/include/CGAL/CLN/cl_integer.h
@@ -41,12 +41,16 @@ inline double	to_double	(const cl_I &I) { return cl_double_approx(I); }
 
 // Specialized utilities.
 
+namespace NTS {
+
 inline bool is_negative		(const cl_I &I) { return minusp(I); } 
 inline bool is_positive		(const cl_I &I) { return plusp(I); }
 inline bool is_zero		(const cl_I &I) { return zerop(I); }
 inline Comparison_result compare (const cl_I &I, const cl_I &J)
 { return Comparison_result(cl_compare(I,J)); }
 
+} // namespace NTS
+
 CGAL_END_NAMESPACE
 
 // #ifdef CGAL_INTERVAL_ARITHMETIC_H
diff --git a/Old_Packages/CLN/include/CGAL/CLN/cl_lfloat.h b/Old_Packages/CLN/include/CGAL/CLN/cl_lfloat.h
index e025c1297b1..abb7f7317f9 100644
--- a/Old_Packages/CLN/include/CGAL/CLN/cl_lfloat.h
+++ b/Old_Packages/CLN/include/CGAL/CLN/cl_lfloat.h
@@ -36,12 +36,16 @@ inline double	to_double	(const cl_LF &I) { return cl_double_approx(I); }
 
 // Specialized utilities.
 
+namespace NTS {
+
 inline bool is_negative		(const cl_LF &I) { return minusp(I); } 
 inline bool is_positive		(const cl_LF &I) { return plusp(I); }
 inline bool is_zero		(const cl_LF &I) { return zerop(I); }
 inline Comparison_result compare (const cl_LF &I, const cl_LF &J)
 { return Comparison_result(cl_compare(I,J)); }
 
+} // namespace NTS
+
 CGAL_END_NAMESPACE
 
 // #ifdef CGAL_INTERVAL_ARITHMETIC_H
diff --git a/Old_Packages/CLN/include/CGAL/CLN/cl_number.h b/Old_Packages/CLN/include/CGAL/CLN/cl_number.h
index 4a860a9a687..45abdc53d5c 100644
--- a/Old_Packages/CLN/include/CGAL/CLN/cl_number.h
+++ b/Old_Packages/CLN/include/CGAL/CLN/cl_number.h
@@ -36,12 +36,16 @@ inline double	to_double	(const cl_number &I) { return cl_double_approx(I); }
 
 // Specialized utilities.
 
+namespace NTS {
+
 inline bool is_negative		(const cl_number &I) { return minusp(I); } 
 inline bool is_positive		(const cl_number &I) { return plusp(I); }
 inline bool is_zero		(const cl_number &I) { return zerop(I); }
 inline Comparison_result compare (const cl_number &I, const cl_number &J)
 { return Comparison_result(cl_compare(I,J)); }
 
+} // namespace NTS
+
 CGAL_END_NAMESPACE
 
 // #ifdef CGAL_INTERVAL_ARITHMETIC_H
diff --git a/Old_Packages/CLN/include/CGAL/CLN/cl_rational.h b/Old_Packages/CLN/include/CGAL/CLN/cl_rational.h
index 956195bc0f8..da51f5e7b05 100644
--- a/Old_Packages/CLN/include/CGAL/CLN/cl_rational.h
+++ b/Old_Packages/CLN/include/CGAL/CLN/cl_rational.h
@@ -36,12 +36,16 @@ inline double	to_double	(const cl_RA &I) { return cl_double_approx(I); }
 
 // Specialized utilities.
 
+namespace NTS {
+
 inline bool is_negative		(const cl_RA &I) { return minusp(I); } 
 inline bool is_positive		(const cl_RA &I) { return plusp(I); }
 inline bool is_zero		(const cl_RA &I) { return zerop(I); }
 inline Comparison_result compare (const cl_RA &I, const cl_RA &J)
 { return Comparison_result(cl_compare(I,J)); }
 
+} // namespace NTS
+
 CGAL_END_NAMESPACE
 
 // #ifdef CGAL_INTERVAL_ARITHMETIC_H
diff --git a/Old_Packages/CLN/include/CGAL/CLN/cl_real.h b/Old_Packages/CLN/include/CGAL/CLN/cl_real.h
index c706c5ba3e3..532c5674f0f 100644
--- a/Old_Packages/CLN/include/CGAL/CLN/cl_real.h
+++ b/Old_Packages/CLN/include/CGAL/CLN/cl_real.h
@@ -36,12 +36,16 @@ inline double	to_double	(const cl_R &I) { return cl_double_approx(I); }
 
 // Specialized utilities.
 
+namespace NTS {
+
 inline bool is_negative		(const cl_R &I) { return minusp(I); } 
 inline bool is_positive		(const cl_R &I) { return plusp(I); }
 inline bool is_zero		(const cl_R &I) { return zerop(I); }
 inline Comparison_result compare (const cl_R &I, const cl_R &J)
 { return Comparison_result(cl_compare(I,J)); }
 
+} // namespace NTS
+
 CGAL_END_NAMESPACE
 
 // #ifdef CGAL_INTERVAL_ARITHMETIC_H
diff --git a/Old_Packages/CLN/include/CGAL/CLN/cl_sfloat.h b/Old_Packages/CLN/include/CGAL/CLN/cl_sfloat.h
index 7b22b9e4974..2d694380393 100644
--- a/Old_Packages/CLN/include/CGAL/CLN/cl_sfloat.h
+++ b/Old_Packages/CLN/include/CGAL/CLN/cl_sfloat.h
@@ -36,12 +36,16 @@ inline double	to_double	(const cl_SF &I) { return cl_double_approx(I); }
 
 // Specialized utilities.
 
+namespace NTS {
+
 inline bool is_negative		(const cl_SF &I) { return minusp(I); } 
 inline bool is_positive		(const cl_SF &I) { return plusp(I); }
 inline bool is_zero		(const cl_SF &I) { return zerop(I); }
 inline Comparison_result compare (const cl_SF &I, const cl_SF &J)
 { return Comparison_result(cl_compare(I,J)); }
 
+} // namespace NTS
+
 CGAL_END_NAMESPACE
 
 // #ifdef CGAL_INTERVAL_ARITHMETIC_H