diff --git a/src/OpenMesh/Core/Mesh/IteratorsT.hh b/src/OpenMesh/Core/Mesh/IteratorsT.hh
index ec12b4b6..42a93c67 100644
--- a/src/OpenMesh/Core/Mesh/IteratorsT.hh
+++ b/src/OpenMesh/Core/Mesh/IteratorsT.hh
@@ -97,11 +97,15 @@ public:
   typedef typename Mesh::VertexHandle         value_handle;
 
 #if 0
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef const value_type&    reference;
   typedef const value_type*    pointer;
   typedef const Mesh*          mesh_ptr;
   typedef const Mesh&          mesh_ref;
 #else
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef value_type&          reference;
   typedef value_type*          pointer;
   typedef Mesh*                mesh_ptr;
@@ -109,8 +113,6 @@ public:
 #endif
 
 
-
-
   /// Default constructor.
   VertexIterT() 
     : mesh_(0), skip_bits_(0) 
@@ -259,11 +261,15 @@ public:
   typedef typename Mesh::VertexHandle         value_handle;
 
 #if 1
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef const value_type&    reference;
   typedef const value_type*    pointer;
   typedef const Mesh*          mesh_ptr;
   typedef const Mesh&          mesh_ref;
 #else
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef value_type&          reference;
   typedef value_type*          pointer;
   typedef Mesh*                mesh_ptr;
@@ -421,11 +427,15 @@ public:
   typedef typename Mesh::HalfedgeHandle         value_handle;
 
 #if 0
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef const value_type&    reference;
   typedef const value_type*    pointer;
   typedef const Mesh*          mesh_ptr;
   typedef const Mesh&          mesh_ref;
 #else
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef value_type&          reference;
   typedef value_type*          pointer;
   typedef Mesh*                mesh_ptr;
@@ -583,11 +593,15 @@ public:
   typedef typename Mesh::HalfedgeHandle         value_handle;
 
 #if 1
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef const value_type&    reference;
   typedef const value_type*    pointer;
   typedef const Mesh*          mesh_ptr;
   typedef const Mesh&          mesh_ref;
 #else
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef value_type&          reference;
   typedef value_type*          pointer;
   typedef Mesh*                mesh_ptr;
@@ -745,11 +759,15 @@ public:
   typedef typename Mesh::EdgeHandle         value_handle;
 
 #if 0
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef const value_type&    reference;
   typedef const value_type*    pointer;
   typedef const Mesh*          mesh_ptr;
   typedef const Mesh&          mesh_ref;
 #else
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef value_type&          reference;
   typedef value_type*          pointer;
   typedef Mesh*                mesh_ptr;
@@ -907,11 +925,15 @@ public:
   typedef typename Mesh::EdgeHandle         value_handle;
 
 #if 1
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef const value_type&    reference;
   typedef const value_type*    pointer;
   typedef const Mesh*          mesh_ptr;
   typedef const Mesh&          mesh_ref;
 #else
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef value_type&          reference;
   typedef value_type*          pointer;
   typedef Mesh*                mesh_ptr;
@@ -1069,11 +1091,15 @@ public:
   typedef typename Mesh::FaceHandle         value_handle;
 
 #if 0
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef const value_type&    reference;
   typedef const value_type*    pointer;
   typedef const Mesh*          mesh_ptr;
   typedef const Mesh&          mesh_ref;
 #else
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef value_type&          reference;
   typedef value_type*          pointer;
   typedef Mesh*                mesh_ptr;
@@ -1231,11 +1257,15 @@ public:
   typedef typename Mesh::FaceHandle         value_handle;
 
 #if 1
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef const value_type&    reference;
   typedef const value_type*    pointer;
   typedef const Mesh*          mesh_ptr;
   typedef const Mesh&          mesh_ref;
 #else
+  typedef std::bidirectional_iterator_tag iterator_category;
+  typedef ptrdiff_t            difference_type;
   typedef value_type&          reference;
   typedef value_type*          pointer;
   typedef Mesh*                mesh_ptr;