diff --git a/leobject/lefactory.py b/leobject/lefactory.py
index 012abf8..05a40d1 100644
--- a/leobject/lefactory.py
+++ b/leobject/lefactory.py
@@ -64,11 +64,13 @@ class LeFactory(object):
     @staticmethod
     def emclass_pycode(model, emclass):
         cls_fields = dict()
-        cls_linked_types = list()
+        cls_linked_types = dict() #keys are LeType classnames and values are tuples (attr_fieldname, attr_fieldtype)
         #Populating linked_type attr
         for rfield in [ f for f in emclass.fields() if f.fieldtype == 'rel2type']:
             fti = rfield.fieldtype_instance()
-            cls_linked_types.append(LeFactory.name2classname(model.component(fti.rel_to_type_id).name))
+            cls_linked_types[LeFactory.name2classname(model.component(fti.rel_to_type_id).name)] = [
+                (f.name, LeFactory.fieldtype_construct_from_field(f)) for f in model.components('EmField') if f.rel_field_id == rfield.uid 
+            ]
         # Populating fieldtype attr
         for field in emclass.fields(relational = False):
             cls_fields[field.name] = LeFactory.fieldtype_construct_from_field(field)
@@ -90,7 +92,16 @@ class LeFactory(object):
 """.format(
             name = LeFactory.name2classname(emclass.name),
             ftypes = "{" + (','.join(['\n\t%s:%s' % (repr(f), v) for f, v in cls_fields.items()])) + "\n}",
-            ltypes = "{" + (','.join(cls_linked_types)) + '}',
+
+            ltypes = '{'+ (','.join(
+                [
+                    '\n\t{ltname}:{ltattr_list}'.format(
+                        ltname = lt,
+                        ltattr_list = '['+(','.join([
+                            '(%s,%s)'%(repr(ltname), ltftype) for ltname, ltftype in ltattr
+                        ]))+']'
+                    ) for lt, ltattr in cls_linked_types.items()
+                ]))+'}',
             fgroups = repr(cls_fieldgroup),
             classtype = repr(emclass.classtype)
         )
diff --git a/leobject/letype.py b/leobject/letype.py
index 2beadb6..3483cf5 100644
--- a/leobject/letype.py
+++ b/leobject/letype.py
@@ -99,7 +99,7 @@ class LeType(object):
     def del_superior(self, leo, nature):
         if nature is None:
             raise ValueError('The argument nature cannot be None')
-        return self._datasource(leo.lodel_id, self.lodel_id, nature)
+        return self._datasource(leo, self, nature)
 
     ## @brief Get the linked objects lodel_id
     # @return an array of lodel_id linked with this object
@@ -110,20 +110,28 @@ class LeType(object):
     ## @brief Link this object with a LeObject
     # @note rel2type
     # @param leo LeObject : The object to be linked with
+    # @param **rel_attr : keywords arguments for relations attributes
     # @return True if success False allready done
     # @throw A Leo exception if the link is not allowed
     # @todo unit tests
     # @todo find a value for depth and rank....
-    def link_to(self, leo):
-        if leo.__class__ not in self._linked_types:
+    def link_to(self, leo, **rel_attr):
+        if leo.__class__ not in self._linked_types.keys():
             raise leobject.leobject.LeObjectError("Constraint error : %s cannot be linked with %s"%(self.__class__.__name__, leo.__class__.__name__))
-        return self._datasource.add_relation(self.lodel_id, leo.lodel_id)
+
+        for attr_name in rel_attr.keys():
+            if attr_name not in [ f for f,g in self._linked_types[leo.__class__] ]:
+                raise AttributeError("A rel2type between a %s and a %s doesn't have an attribute %s"%(self.__class__.__name__, leo.__class__.__name__, attr_name))
+            if not self._linked_types[leo.__class__][1].check(rel_attr[attr_name]):
+                raise ValueError("Wrong value '%s' for attribute %s"%(rel_attr[attr_name], attr_name))
+
+        return self._datasource.add_relation(self, leo, nature=None, depth=None, rank=None, **rel_attr)
 
     ## @brief Remove a link bewteen this object and another
     # @param leo LeObject : A LeObject instance linked with self
     # @todo unit tests
     def unlink(self, leo):
-        return self._datasource.del_relation(self.lodel_id, leo.lodel_id)
+        return self._datasource.del_relation(self, leo)
         
     ## @brief Delete a LeType from the datasource
     # @param filters list : list of filters (see @ref leobject_filters)