diff --git a/account_usability/account.py b/account_usability/account.py
index 4285c39..4430335 100644
--- a/account_usability/account.py
+++ b/account_usability/account.py
@@ -57,48 +57,6 @@ class AccountInvoice(models.Model):
     #    return res
 
 
-    # for report
-    @api.multi
-    def py3o_lines_layout(self):
-        self.ensure_one()
-        res1 = []
-        # [
-        #    {'categ': categ(6), 'lines': [l1, l2], 'subtotal': 23.32},
-        #    {'categ': categ(1), 'lines': [l3, l4, l5], 'subtotal': 12.42},
-        # ]
-        for categ, lines in\
-                groupby(self.invoice_line_ids, lambda l: l.layout_category_id):
-            entry = {'lines': [], 'categ': categ}
-            if categ.subtotal:
-                entry['subtotal'] = 0.0
-            for line in lines:
-                entry['lines'].append(line)
-                if 'subtotal' in entry:
-                    entry['subtotal'] += line.price_subtotal
-            res1.append(entry)
-        res2 = []
-        if len(res1) == 1 and not res1[0]['categ']:
-            # No category at all
-            for l in res1[0]['lines']:
-                res2.append({'line': l})
-        else:
-            # TODO : gérer qd il n'y a pas de categ
-            for ldict in res1:
-                res2.append({'categ': ldict['categ']})
-                for line in ldict['lines']:
-                    res2.append({'line': line})
-                if 'subtotal' in ldict:
-                    res2.append({'subtotal': ldict['subtotal']})
-        # res2:
-        # [
-        #    {'categ': categ(1)},
-        #    {'line': invoice_line(2)},
-        #    {'line': invoice_line(3)},
-        #    {'subtotal': 8932.23},
-        # ]
-        return res2
-
-
 class AccountInvoiceLine(models.Model):
     _inherit = 'account.invoice.line'
 
diff --git a/sale_usability/sale.py b/sale_usability/sale.py
index 65315aa..3d7cee0 100644
--- a/sale_usability/sale.py
+++ b/sale_usability/sale.py
@@ -75,9 +75,56 @@ class SaleOrder(models.Model):
         # ]
         return res2
 
+
 class ProcurementGroup(models.Model):
     _inherit = 'procurement.group'
 
     sale_ids = fields.One2many(
         'sale.order', 'procurement_group_id', string='Sale Orders',
         readonly=True)
+
+
+class AccountInvoice(models.Model):
+    _inherit = 'account.invoice'
+
+    # for report (located in sale_usability and not account_usability
+    # because it uses layout categ defined in sale
+    @api.multi
+    def py3o_lines_layout(self):
+        self.ensure_one()
+        res1 = []
+        # [
+        #    {'categ': categ(6), 'lines': [l1, l2], 'subtotal': 23.32},
+        #    {'categ': categ(1), 'lines': [l3, l4, l5], 'subtotal': 12.42},
+        # ]
+        for categ, lines in\
+                groupby(self.invoice_line_ids, lambda l: l.layout_category_id):
+            entry = {'lines': [], 'categ': categ}
+            if categ.subtotal:
+                entry['subtotal'] = 0.0
+            for line in lines:
+                entry['lines'].append(line)
+                if 'subtotal' in entry:
+                    entry['subtotal'] += line.price_subtotal
+            res1.append(entry)
+        res2 = []
+        if len(res1) == 1 and not res1[0]['categ']:
+            # No category at all
+            for l in res1[0]['lines']:
+                res2.append({'line': l})
+        else:
+            # TODO : gérer qd il n'y a pas de categ
+            for ldict in res1:
+                res2.append({'categ': ldict['categ']})
+                for line in ldict['lines']:
+                    res2.append({'line': line})
+                if 'subtotal' in ldict:
+                    res2.append({'subtotal': ldict['subtotal']})
+        # res2:
+        # [
+        #    {'categ': categ(1)},
+        #    {'line': invoice_line(2)},
+        #    {'line': invoice_line(3)},
+        #    {'subtotal': 8932.23},
+        # ]
+        return res2