diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt
index 856d074ddc5..e065e920abf 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Arrangement_on_surface_2.txt
@@ -3573,12 +3573,11 @@ of the curves.
 The `AosApproximateTraits_2` refines the concept
 `AosApproximatePointTraits_2`. In addition to the type
 `Approximate_number_type` required by the latter, a model of the
-`AosApproximateTraits_2` concept must define the types
-`Approximate_kernel` and `Approximate_point_2`, which are
-typically defined as `CGAL::Cartesian<Approximate_number_type>`
-and `Approximate_kernel::Point_2`, respectively. Also, it
-must support the operations below (in addition to the operation
-required by the concept `AosApproximatePointTraits_2`).
+`AosApproximateTraits_2` concept must define the type
+`Approximate_point_2`, which is typically defined as
+`CGAL::Cartesian<Approximate_number_type>::Point_2`. Also, it must
+support the operations below (in addition to the operation required by
+the concept `AosApproximatePointTraits_2`).
 
 <DL>
 <DT>\link AosApproximateTraits_2::Approximate_2 <B>`Approximate_2`</B>\endlink:
diff --git a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/AosApproximateTraits_2.h b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/AosApproximateTraits_2.h
index 503fbd889e0..2020e723039 100644
--- a/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/AosApproximateTraits_2.h
+++ b/Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/AosApproximateTraits_2.h
@@ -24,9 +24,6 @@ public:
   /// \name Types
   /// @{
 
-  //! the approximate kernel.
-  typedef unspecified_type Approximate_kernel;
-
   //! the approximate point.
   typedef unspecified_type Approximate_point_2;