diff --git a/mis_builder/__openerp__.py b/mis_builder/__openerp__.py
old mode 100755
new mode 100644
diff --git a/mis_builder/models/accounting_none.py b/mis_builder/models/accounting_none.py
old mode 100755
new mode 100644
index bcf15ecb..57f7f549
--- a/mis_builder/models/accounting_none.py
+++ b/mis_builder/models/accounting_none.py
@@ -1,11 +1,13 @@
 # -*- coding: utf-8 -*-
-
-
+# © 2016 Thomas Binsfeld
+# © 2016 ACSONE SA/NV (<http://acsone.eu>)
+# License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl.html).
 """
-Provides the AccountingNone singleton
+Provides the AccountingNone singleton.
 
 AccountingNone is a null value that dissolves in basic arithmetic operations,
-as illustrated in the examples below
+as illustrated in the examples below. In comparisons, AccountingNone behaves
+the same as zero.
 
 >>> 1 + 1
 2
@@ -51,8 +53,38 @@ AccountingNone
 AccountingNone
 >>> AccountingNone * None
 AccountingNone
+>>> None * AccountingNone
+AccountingNone
+>>> str(AccountingNone)
+''
+>>> bool(AccountingNone)
+False
+>>> AccountingNone > 0
+False
+>>> AccountingNone < 0
+False
+>>> AccountingNone < 1
+True
+>>> AccountingNone > 1
+False
+>>> 0 < AccountingNone
+False
+>>> 0 > AccountingNone
+False
+>>> 1 < AccountingNone
+False
+>>> 1 > AccountingNone
+True
+>>> AccountingNone == 0
+True
+>>> AccountingNone == 0.0
+True
+>>> AccountingNone == None
+True
 """
 
+__all__ = ['AccountingNone']
+
 
 class AccountingNoneType(object):
 
@@ -89,10 +121,15 @@ class AccountingNoneType(object):
     def __neg__(self):
         return self
 
+    def __div__(self, other):
+        if other is AccountingNone:
+            return AccountingNone
+        return 0.0
+
+    def __rdiv__(self, other):
+        raise ZeroDivisionError
+
     def __floordiv__(self, other):
-        """
-        Overload of the // operator
-        """
         if other is AccountingNone:
             return AccountingNone
         return 0.0
@@ -101,9 +138,6 @@ class AccountingNoneType(object):
         raise ZeroDivisionError
 
     def __truediv__(self, other):
-        """
-        Overload of the / operator
-        """
         if other is AccountingNone:
             return AccountingNone
         return 0.0
@@ -116,17 +150,29 @@ class AccountingNoneType(object):
             return AccountingNone
         return 0.0
 
-    def __rmul__(self, other):
-        if other is None or other is AccountingNone:
-            return AccountingNone
-        return 0.0
+    __rmul__ = __mul__
 
     def __repr__(self):
         return 'AccountingNone'
 
-    def __unicode__(self):
+    def __str__(self):
         return ''
 
+    def __nonzero__(self):
+        return False
+
+    def __bool__(self):
+        return False
+
+    def __eq__(self, other):
+        return other == 0 or other is None or other is AccountingNone
+
+    def __lt__(self, other):
+        return 0 < other
+
+    def __gt__(self, other):
+        return 0 > other
+
 
 AccountingNone = AccountingNoneType()
 
diff --git a/mis_builder/models/aep.py b/mis_builder/models/aep.py
old mode 100755
new mode 100644
diff --git a/mis_builder/models/mis_builder.py b/mis_builder/models/mis_builder.py
old mode 100755
new mode 100644