diff --git a/knowledge/interfaces.py b/knowledge/interfaces.py
index 4cffe4f..144ade6 100644
--- a/knowledge/interfaces.py
+++ b/knowledge/interfaces.py
@@ -1,5 +1,5 @@
 #
-#  Copyright (c) 2006 Helmut Merz helmutm@cy55.de
+#  Copyright (c) 2011 Helmut Merz helmutm@cy55.de
 #
 #  This program is free software; you can redistribute it and/or modify
 #  it under the terms of the GNU General Public License as published by
@@ -26,7 +26,7 @@ from zope.interface import Interface, Attribute
 from zope import schema
 from zope.i18nmessageid import MessageFactory
 
-_ = MessageFactory('zope')
+_ = MessageFactory('cybertools.knowledge')
 
 
 class IKnowledgeElement(Interface):
@@ -69,6 +69,9 @@ class IKnowing(Interface):
     """ Someone who knows something.
     """
 
+    knowledge = Attribute('A set of knowledge elements that this object '
+            'knows about.')
+
     def getKnowledge():
         """ Return the collection of elements that constitute the
             knowledge of this object.