diff --git a/Arrangement_on_surface_2/include/CGAL/Arr_tags.h b/Arrangement_on_surface_2/include/CGAL/Arr_tags.h
index a59663be012..56a9c2f6183 100644
--- a/Arrangement_on_surface_2/include/CGAL/Arr_tags.h
+++ b/Arrangement_on_surface_2/include/CGAL/Arr_tags.h
@@ -16,10 +16,18 @@
 // 
 //
 // Author(s): Efi Fogel         <efif@post.tau.ac.il>
+//            Eric Berberich    <ericb@post.tau.ac.il>
 
 #ifndef CGAL_ARR_TAGS_H
 #define CGAL_ARR_TAGS_H
 
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/and.hpp>
+#include <boost/mpl/or.hpp>
+#include <boost/mpl/not.hpp>
+#include <boost/mpl/logical.hpp>
+
 /*! \file
  * Definition of the tags for the arrangement package.
  */
@@ -41,6 +49,131 @@ struct Arr_closed_side_tag : public virtual Arr_boundary_side_tag {};
 struct Arr_contracted_side_tag : public virtual Arr_boundary_side_tag {};
 struct Arr_identified_side_tag : public virtual Arr_boundary_side_tag {};
 
+
+/*!\brief Struct to determine whether all side tags are "oblivious"
+ */
+template < class ArrLeftSideTag, class ArrBottomSideTag, 
+           class ArrTopSideTag, class ArrRightSideTag >
+struct Arr_all_sides_oblivious_tag {
+
+    //! This instance's first template parameter
+    typedef ArrLeftSideTag   Arr_left_side_tag;
+    
+    //! This instance's second template parameter
+    typedef ArrBottomSideTag Arr_bottom_side_tag;
+
+    //! This instance's third template parameter
+    typedef ArrTopSideTag    Arr_top_side_tag;
+
+    //! This instance's fourth template parameter
+    typedef ArrRightSideTag  Arr_right_side_tag;
+
+private:
+
+    typedef boost::mpl::bool_< true > true_;
+    typedef boost::mpl::bool_< false > false_;
+
+    typedef boost::mpl::if_< 
+       boost::is_same< Arr_left_side_tag, Arr_oblivious_side_tag >,
+       true_, false_ > 
+    Left_oblivious;
+
+    typedef boost::mpl::if_< 
+       boost::is_same< Arr_bottom_side_tag, Arr_oblivious_side_tag >,
+       true_, false_ > 
+    Bottom_oblivious;
+
+    typedef boost::mpl::if_< 
+       boost::is_same< Arr_top_side_tag, Arr_oblivious_side_tag >,
+       true_, false_ > 
+    Top_oblivious;
+
+    typedef boost::mpl::if_< 
+       boost::is_same< Arr_right_side_tag, Arr_oblivious_side_tag >,
+       true_, false_ > 
+    Right_oblivious;
+
+public:
+
+    /*!\brief
+     * boolean tag that is bool<true> if all sides are oblivious, 
+     * otherwise bool<false>
+     */
+    typedef boost::mpl::and_< Left_oblivious, Bottom_oblivious, 
+                              Top_oblivious, Right_oblivious > result;
+};
+
+
+/*!\brief Struct to check consistent tagging of identifications
+ */
+template < class ArrLeftSideTag, class ArrBottomSideTag, 
+           class ArrTopSideTag, class ArrRightSideTag >
+struct Arr_sane_identified_tagging {
+
+    //! This instance's first template parameter
+    typedef ArrLeftSideTag   Arr_left_side_tag;
+    
+    //! This instance's second template parameter
+    typedef ArrBottomSideTag Arr_bottom_side_tag;
+
+    //! This instance's third template parameter
+    typedef ArrTopSideTag    Arr_top_side_tag;
+
+    //! This instance's fourth template parameter
+    typedef ArrRightSideTag  Arr_right_side_tag;
+
+private:
+
+    typedef boost::mpl::bool_< true > true_;
+    typedef boost::mpl::bool_< false > false_;
+
+    typedef boost::mpl::if_< 
+       boost::is_same< Arr_left_side_tag, Arr_identified_side_tag >,
+       true_, false_ > 
+    Left_identified;
+
+    typedef boost::mpl::if_< 
+       boost::is_same< Arr_bottom_side_tag, Arr_identified_side_tag >,
+       true_, false_ > 
+    Bottom_identified;
+
+    typedef boost::mpl::if_< 
+       boost::is_same< Arr_top_side_tag, Arr_identified_side_tag >,
+       true_, false_ > 
+    Top_identified;
+
+    typedef boost::mpl::if_< 
+       boost::is_same< Arr_right_side_tag, Arr_identified_side_tag >,
+       true_, false_ > 
+    Right_identified;
+
+    typedef boost::mpl::and_< Left_identified, Right_identified > 
+    LR_identified;
+
+    typedef boost::mpl::and_< Bottom_identified, Top_identified > 
+    BT_identified;
+
+    typedef boost::mpl::and_< boost::mpl::not_< Left_identified>,
+                              boost::mpl::not_< Right_identified > >
+    LR_non_identified;
+
+    typedef boost::mpl::and_< boost::mpl::not_< Bottom_identified >, 
+                              boost::mpl::not_< Top_identified > > 
+    BT_non_identified;
+
+    typedef boost::mpl::or_< LR_identified, LR_non_identified > LR_ok;
+    typedef boost::mpl::or_< BT_identified, BT_non_identified > BT_ok;
+
+public:
+
+    /*!\brief
+     * boolean tag that is bool<true> if opposite sides are either 
+     * both identified or both non-identified,
+     * otherwise bool<false>
+     */
+    typedef boost::mpl::and_< LR_ok, BT_ok > result;
+};
+
 CGAL_END_NAMESPACE
 
 #endif