diff --git a/hurricane/src/hurricane/BasicLayer.cpp b/hurricane/src/hurricane/BasicLayer.cpp
index 448b9f10..636e6b6f 100644
--- a/hurricane/src/hurricane/BasicLayer.cpp
+++ b/hurricane/src/hurricane/BasicLayer.cpp
@@ -209,6 +209,14 @@ namespace Hurricane {
   { return BasicLayer_BasicLayers(this); }
 
 
+  const Layer* BasicLayer::getTop () const
+  { return this; }
+
+
+  const Layer* BasicLayer::getBottom () const
+  { return this; }
+
+
   void BasicLayer::_postCreate ()
   {
     Mask basicLayersMask = 0;
diff --git a/hurricane/src/hurricane/hurricane/BasicLayer.h b/hurricane/src/hurricane/hurricane/BasicLayer.h
index 9d332c06..07658ba1 100644
--- a/hurricane/src/hurricane/hurricane/BasicLayer.h
+++ b/hurricane/src/hurricane/hurricane/BasicLayer.h
@@ -95,6 +95,8 @@ namespace Hurricane {
       inline  unsigned        getGds2Datatype        () const;
       virtual BasicLayers     getBasicLayers         () const;
       virtual BasicLayer*     getBlockageLayer       () const;
+      virtual const Layer*    getTop                 () const;
+      virtual const Layer*    getBottom              () const;
       inline  const Name&     getRealName            () const;
     // Updators                                      
       inline  void            setBlockageLayer       ( BasicLayer* layer);