--- a/src/catedit/api.py	Wed Dec 03 17:40:19 2014 +0100
+++ b/src/catedit/api.py	Tue Dec 09 12:39:38 2014 +0100
@@ -47,7 +47,7 @@
                 args["property_predicate"],
                 args["property_object"]):
             if property_object:
-                property_object_to_append=property_object
+                property_object_to_append = property_object
                 # if URIRef category, we must prefix id with namespace
                 if app.config["PROPERTY_LIST"] \
                              [property_predicate] \
@@ -55,7 +55,8 @@
                     property_object_to_append = app.config["ONTOLOGY_NAMESPACE"] \
                                                 + property_object
                     # print property_object_to_append
-                new_property_list.append((property_predicate, property_object_to_append))
+                new_property_list.append((property_predicate,
+                                          property_object_to_append))
         # print new_property_list
         c = cat_manager_instance.load_cat(cat_id)
         c.edit_category(new_description=args["description"],

--- a/src/catedit/app.py	Wed Dec 03 17:40:19 2014 +0100
+++ b/src/catedit/app.py	Tue Dec 09 12:39:38 2014 +0100
@@ -14,19 +14,21 @@
 github = GitHub(app)
 
 # set up logging
-file_handler = FileHandler(filename=app.config["LOG_FILE_PATH"])
-file_handler.setFormatter(Formatter('''
-Message type:       %(levelname)s
-Location:           %(pathname)s:%(lineno)d
-Module:             %(module)s
-Function:           %(funcName)s
-Time:               %(asctime)s
+if app.config["LOGGING"]:
+    file_handler = FileHandler(filename=app.config["LOG_FILE_PATH"])
+    file_handler.setFormatter(Formatter('''
+    Message type:       %(levelname)s
+    Location:           %(pathname)s:%(lineno)d
+    Module:             %(module)s
+    Function:           %(funcName)s
+    Time:               %(asctime)s
 
-Message:
+    Message:
 
-%(message)s
-'''))
-app.logger.addHandler(file_handler)
+    %(message)s
+    '''))
+    app.logger.addHandler(file_handler)
+    app.logger.setLevel(app.config["LOGGING_LEVEL"])
 
 # session management
 

--- a/src/catedit/models.py	Wed Dec 03 17:40:19 2014 +0100
+++ b/src/catedit/models.py	Tue Dec 09 12:39:38 2014 +0100
@@ -92,7 +92,8 @@
         """
         Checks if there is a new label and if so apply changes
         """
-        if new_label is not False and new_label != self.label:
+        if new_label is not (False or None) and \
+           new_label != self.label:
             self.cat_graph.remove((self.this_category,
                                    RDFS.label,
                                    self.cat_graph.label(self.this_category)))
@@ -103,7 +104,8 @@
         """
         Checks if there is a new description and if so apply changes
         """
-        if new_description is not False and new_description != self.description:
+        if new_description is not (False or None) and \
+           new_description != self.description:
             self.cat_graph.remove((self.this_category,
                                   RDF.Description,
                                   self.cat_graph.value(self.this_category,

--- a/src/catedit/settings.py	Wed Dec 03 17:40:19 2014 +0100
+++ b/src/catedit/settings.py	Tue Dec 09 12:39:38 2014 +0100
@@ -1,4 +1,5 @@
 from rdflib import *
+from rdflib.namespace import SKOS
 
 
 class appSettings(object):
@@ -8,6 +9,7 @@
     HOST = "0.0.0.0"
     DEBUG = True
     LOGGING = False
+    LOGGING_LEVEL = "DEBUG"
 
     # WTForms settings
 
@@ -37,7 +39,7 @@
     GITHUB_CLIENT_ID = "3e31f3b000a4914f75ef"
     GITHUB_CLIENT_SECRET = "bc17eb0ec11385628c2e75aacb5ff8ef5f29e490"
 
-    # Property List - DO NOT OVERWRITE IN config.py EVER
+    # Property List
 
     PROPERTY_LIST = {
         "subClassOf": {
@@ -68,6 +70,13 @@
             "rdflib_class": RDFS.Resource,
             "object_rdflib_class": URIRef,
         },
+        "related": {
+            "descriptive_label_fr": "En relation avec",
+            "descriptive_label_en": "Related to",
+            "object_type": "uriref-category",
+            "rdflib_class": SKOS.related,
+            "object_rdflib_class": URIRef,
+        }
     }
 
     # Category persistence parameters