diff --git a/owlps-positioning/calibrationrequest.cc b/owlps-positioning/calibrationrequest.cc
index 11fec96..9e1f2ba 100644
--- a/owlps-positioning/calibrationrequest.cc
+++ b/owlps-positioning/calibrationrequest.cc
@@ -1,14 +1,22 @@
 #include "calibrationrequest.hh"
+#include "referencepoint.hh"
 
 
 
 /* *** Write accessors *** */
 
 
+void CalibrationRequest::reference_point_backward_link() const
+{
+  reference_point->add_request(this) ;
+}
+
+
 void CalibrationRequest::clear()
 {
   Request::clear() ;
   reference_point = NULL ;
+  direction.clear() ;
 }
 
 
@@ -23,6 +31,7 @@ CalibrationRequest::operator=(const CalibrationRequest &source)
     return *this ;
 
   this->Request::operator=(source) ;
+  direction = source.direction ;
   reference_point = source.reference_point ;
 
   return *this ;
@@ -36,5 +45,6 @@ bool CalibrationRequest::operator==(const CalibrationRequest &source)
 
   return
     this->Request::operator==(source) &&
+    direction == source.direction &&
     reference_point == source.reference_point ;
 }
diff --git a/owlps-positioning/calibrationrequest.hh b/owlps-positioning/calibrationrequest.hh
index 658f760..de4b102 100644
--- a/owlps-positioning/calibrationrequest.hh
+++ b/owlps-positioning/calibrationrequest.hh
@@ -4,6 +4,7 @@
 class ReferencePoint ;
 
 #include "request.hh"
+#include "direction.hh"
 
 /// Represents a calibration Request sent by a mobile
 class CalibrationRequest: public Request
@@ -11,30 +12,42 @@ class CalibrationRequest: public Request
 protected:
   /// The reference point the mobile calibrates
   ReferencePoint *reference_point ;
+  /// The direction in which the mobile was during the measurement
+  Direction direction ;
 
 public:
-  CalibrationRequest(void): reference_point(NULL) {}
+  CalibrationRequest(void):
+    reference_point(NULL), direction(Direction()) {}
   /// Copy constructor
   CalibrationRequest(const CalibrationRequest &source):
-    Request(source), reference_point(source.reference_point) {}
+    Request(source), reference_point(source.reference_point),
+    direction(source.direction) {}
   /// \brief Constructs a CalibrationRequest from a Request and
-  /// (possibly) a ReferencePoint)
+  /// possibly a ReferencePoint and a Direction)
   CalibrationRequest(const Request &source,
-                     ReferencePoint *_reference_point = NULL):
-    Request(source), reference_point(_reference_point) {}
+                     ReferencePoint *_reference_point = NULL,
+                     const Direction &_direction = Direction()):
+    Request(source), reference_point(_reference_point),
+    direction(_direction) {}
 
   ~CalibrationRequest(void) {}
 
   /** @name Read accessors */
   //@{
+  /// #direction read accessor
+  const Direction& get_direction(void) const ;
   /// #reference_point read accessor
   ReferencePoint* get_reference_point(void) const ;
   //@}
 
   /** @name Write accessors */
   //@{
+  /// #direction write accessor
+  void set_direction(const Direction &_direction) ;
   /// #reference_point write accessor
   void set_reference_point(const ReferencePoint *_rp) ;
+  /// Add the CalibrationRequest to the #reference_point list of requests
+  void reference_point_backward_link(void) const ;
   /// Reinitialises all attributes
   void clear(void) ;
   //@}
@@ -58,6 +71,12 @@ inline ReferencePoint* CalibrationRequest::get_reference_point(void) const
 }
 
 
+inline const Direction& CalibrationRequest::get_direction(void) const
+{
+  return direction ;
+}
+
+
 
 /* *** Write accessors *** */
 
@@ -69,6 +88,13 @@ inline void CalibrationRequest::set_reference_point(
 }
 
 
+inline void CalibrationRequest::
+set_direction(const Direction &_direction)
+{
+  direction = _direction ;
+}
+
+
 
 /* *** Operators *** */