diff --git a/product/ERP5/Document/OpenOrder.py b/product/ERP5/Document/OpenOrder.py
index 30085ddac0e572ec4b19c5895463982c80597888..f764d315510ed3ab5b29d72aebba10bc464c0dd5 100644
--- a/product/ERP5/Document/OpenOrder.py
+++ b/product/ERP5/Document/OpenOrder.py
@@ -37,6 +37,10 @@ from Products.ERP5.Document.Supply import Supply
 class OpenOrder(Supply):
   """
     An OpenOrder is a collection of Open Order Lines
+
+    TODO:
+    - make sure that this should be (or not) a subclass
+      of Order
   """
   meta_type = 'ERP5 Open Order'
   portal_type = 'Open Order'
diff --git a/product/ERP5/Document/OpenOrderLine.py b/product/ERP5/Document/OpenOrderLine.py
index 8cc4a4183b20024c012f92fedce3f63c9331f8cf..da93d26ce0c9e3ecfc4ddf614fe57b77c69f5fdb 100644
--- a/product/ERP5/Document/OpenOrderLine.py
+++ b/product/ERP5/Document/OpenOrderLine.py
@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 ##############################################################################
 #
 # Copyright (c) 2009 Nexedi SA and Contributors. All Rights Reserved.
@@ -29,11 +30,16 @@
 from AccessControl import ClassSecurityInfo
 from Products.ERP5Type import Permissions, PropertySheet
 from Products.ERP5.Document.SupplyLine import SupplyLine
+from Products.ERP5.Document.OrderLine import OrderLine
 
-class OpenOrderLine(SupplyLine):
+class OpenOrderLine(SupplyLine, OrderLine):
     """
       An Open Order Line is a Supply Line with additional
       properties to define repeatability
+
+      TODO:
+      - make sure that this should be (or not) a subclass
+        of OrderLine
     """
     meta_type = 'ERP5 Open Order Line'
     portal_type = 'Open Order Line'