diff --git a/purchase.py b/purchase.py
index 8c7500b..00934a3 100644
--- a/purchase.py
+++ b/purchase.py
@@ -1,3 +1,6 @@
+#This file is part of Tryton.  The COPYRIGHT file at the top level of
+#txhis repository contains the full copyright notices and license terms
+
 from trytond.model import ModelView, ModelSQL