diff --git a/cybertools/relation/README.txt b/cybertools/relation/README.txt
index ccf560a..f745bd9 100644
--- a/cybertools/relation/README.txt
+++ b/cybertools/relation/README.txt
@@ -1,8 +1,6 @@
 Quickstart Instructions
 =======================
 
-  ($Id$)
-
 In the ++etc++/default folder of your Zope 3 site create a Unique Id Utility
 and a relation registry.
 
@@ -87,15 +85,16 @@ reference these objects via IntIds later; the __parent__ and __name__
 attributes are also needed later when we send an IObjectRemovedEvent event):
 
   >>> from persistent import Persistent
-  >>> from zope.interface import implements
+  >>> from zope.interface import implementer
   >>> from cybertools.relation.interfaces import IRelatable
 
   >>> class Person(Persistent):
   ...     __name__ = __parent__ = None
-  ...     implements(IRelatable)
+  >>> Person = implementer(IRelatable)(Person)
 
   >>> class City(Persistent):
-  ...     implements(IRelatable)
+  ...     pass
+  >>> City = implementer(IRelatable)(City)
 
   >>> clark = Person()
   >>> kirk = Person()
@@ -396,10 +395,8 @@ We also need a class for the predicate objects that will be used for
 the constructor of the NamedPredicateRelation class:
 
   >>> from cybertools.relation.interfaces import IPredicate
-  >>> from zope.interface import implements
 
   >>> class Predicate(object):
-  ...     implements(IPredicate)
   ...     def __init__(self, name):
   ...         self.name = name
   ...         self.forClass = None
@@ -407,6 +404,7 @@ the constructor of the NamedPredicateRelation class:
   ...         if self.forClass is not None:
   ...             return self.forClass(self, None, None).getPredicateName()
   ...         return self.name
+  >>> Predicate = implementer(IPredicate)(Predicate)
 
 We can now create a predicate with the name '_lives in_' (that may replace
 our LivesIn relation class from above) and use for registration:
diff --git a/cybertools/relation/registry.py b/cybertools/relation/registry.py
index bba0441..8092c04 100644
--- a/cybertools/relation/registry.py
+++ b/cybertools/relation/registry.py
@@ -1,23 +1,6 @@
-#
-#  Copyright (c) 2013 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
-#  the Free Software Foundation; either version 2 of the License, or
-#  (at your option) any later version.
-#
-#  This program is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#  GNU General Public License for more details.
-#
-#  You should have received a copy of the GNU General Public License
-#  along with this program; if not, write to the Free Software
-#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
-#
+# cybertools.relation.registry
 
-"""
-Implementation of the utilities needed for the relations package.
+""" Implementation of the utilities needed for the relations package.
 """
 
 from logging import getLogger
@@ -26,9 +9,9 @@ from persistent import Persistent
 from persistent.interfaces import IPersistent
 from zope import component
 from zope.component import adapts
-from zope.interface import Interface, Attribute, implements
-from zope.app.catalog.catalog import Catalog, ResultSet
-from zope.app.catalog.field import FieldIndex
+from zope.interface import Interface, Attribute, implementer
+from zope.catalog.catalog import Catalog, ResultSet
+from zope.catalog.field import FieldIndex
 from zope.intid.interfaces import IIntIds
 from zope.location.interfaces import ILocation
 from zope.event import notify
@@ -36,18 +19,18 @@ from zope.interface.interfaces import ObjectEvent
 from zope.security.proxy import removeSecurityProxy
 from zope.traversing.api import getName, getParent
 
-from interfaces import IRelationRegistry, IRelationInvalidatedEvent, IRelation
+from cybertools.relation.interfaces import IRelationRegistry
+from cybertools.relation.interfaces import IRelationInvalidatedEvent, IRelation
 
 
 logger = getLogger('cybertools.relation.registry')
 
 
+@implementer(IRelationRegistry)
 class DummyRelationRegistry(object):
     """ Dummy implementation for demonstration and test purposes.
     """
 
-    implements(IRelationRegistry)
-
     def __init__(self):
         self.relations = []
         self.objects = []
@@ -112,12 +95,11 @@ class DummyRelationRegistry(object):
         return result
 
 
+@implementer(IRelationRegistry)
 class RelationRegistry(Catalog):
     """ Local utility for registering (cataloguing) and searching relations.
     """
 
-    implements(IRelationRegistry)
-
     relations = None
 
     def __init__(self, *args, **kw):
@@ -202,12 +184,12 @@ class IIndexableRelation(Interface):
     """
 
 
+@implementer(IIndexableRelation)
 class IndexableRelationAdapter(object):
     """ Adapter for providing the attributes needed for indexing
         relation objects.
     """
 
-    implements(IIndexableRelation)
     adapts(IRelation)
 
     def __init__(self, context):
@@ -296,8 +278,9 @@ def setRelationSingle(relation, forSecond=True):
 
 # events and handlers
 
+@implementer(IRelationInvalidatedEvent)
 class RelationInvalidatedEvent(ObjectEvent):
-    implements(IRelationInvalidatedEvent)
+    pass
 
 
 def invalidateRelations(context, event):
diff --git a/cybertools/relation/tests.py b/cybertools/relation/tests.py
index 22eca20..3142bf8 100755
--- a/cybertools/relation/tests.py
+++ b/cybertools/relation/tests.py
@@ -44,15 +44,15 @@ class TestRelation(unittest.TestCase):
     def testInterfaces(self):
         verifyClass(IPredicate, Relation)
         verifyClass(IRelation, Relation)
-        self.assert_(IDyadicRelation.providedBy(DyadicRelation(None, None)),
+        self.assertTrue(IDyadicRelation.providedBy(DyadicRelation(None, None)),
             'Interface IDyadicRelation is not implemented by class DyadicRelation.')
         verifyClass(IDyadicRelation, DyadicRelation)
-        self.assert_(ITriadicRelation.providedBy(TriadicRelation(None, None, None)),
+        self.assertTrue(ITriadicRelation.providedBy(TriadicRelation(None, None, None)),
              'Interface ITriadicRelation is not implemented by class TriadicRelation.')
         verifyClass(ITriadicRelation, TriadicRelation)
         # avoid dependency on import:
         from cybertools.relation.registry import RelationRegistry
-        self.assert_(IRelationRegistry.providedBy(RelationRegistry()),
+        self.assertTrue(IRelationRegistry.providedBy(RelationRegistry()),
             'Interface IRelationRegistry is not implemented by class RelationRegistry.')
         verifyClass(IRelationRegistry, RelationRegistry)