diff --git a/cybertools/catalog/README.txt b/cybertools/catalog/README.txt
index 6273fb7..cf6a8de 100644
--- a/cybertools/catalog/README.txt
+++ b/cybertools/catalog/README.txt
@@ -16,12 +16,12 @@ for testing purposes here) and a catalog with a few indexes.
   >>> intid = IntIdsStub()
   >>> component.provideUtility(intid)
 
-  >>> from zope.app.catalog.interfaces import ICatalog
-  >>> from zope.app.catalog.catalog import Catalog
+  >>> from zope.catalog.interfaces import ICatalog
+  >>> from zope.catalog.catalog import Catalog
   >>> catalog = Catalog()
   >>> component.provideUtility(catalog, ICatalog)
 
-  >>> from zope.interface import Interface, Attribute, implements
+  >>> from zope.interface import Interface, Attribute, implementer
   >>> class IContent(Interface):
   ...     f1 = Attribute('f1')
   ...     f2 = Attribute('f2')
@@ -30,8 +30,8 @@ for testing purposes here) and a catalog with a few indexes.
   ...     t2 = Attribute('t2')
   ...     k1 = Attribute('k1')
 
-  >>> from zope.app.catalog.field import FieldIndex
-  >>> from zope.app.catalog.text import TextIndex
+  >>> from zope.catalog.field import FieldIndex
+  >>> from zope.catalog.text import TextIndex
   >>> from cybertools.catalog.keyword import KeywordIndex
   >>> catalog['f1'] = FieldIndex('f1', IContent)
   >>> catalog['f2'] = FieldIndex('f2', IContent)
@@ -45,7 +45,6 @@ to index and query.
 
   >>> from zope.app.container.contained import Contained
   >>> class Content(Contained):
-  ...     implements(IContent)
   ...     def __init__(self, id, f1='', f2='', f3='', t1='', t2='', k1=[]):
   ...         self.id = id
   ...         self.f1 = f1
@@ -56,6 +55,7 @@ to index and query.
   ...         self.k1 = k1
   ...     def __cmp__(self, other):
   ...         return cmp(self.id, other.id)
+  >>> Content = implementer(IContent)(Content)
 
 The id attribute is just so we can identify objects we find again
 easily. By including the __cmp__ method we make sure search results
diff --git a/cybertools/catalog/keyword.py b/cybertools/catalog/keyword.py
index 4b362a2..9453d96 100644
--- a/cybertools/catalog/keyword.py
+++ b/cybertools/catalog/keyword.py
@@ -1,43 +1,25 @@
-#
-#  Copyright (c) 2008 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.catalog.keyword
 
 """Keyword catalog index.
-
-$Id$
 """
 
 import zope.index.keyword
 import zope.interface
 
 import zope.app.container.contained
-import zope.app.catalog.attribute
-import zope.app.catalog.interfaces
+import zope.catalog.attribute
+import zope.catalog.interfaces
 
 
-class IKeywordIndex(zope.app.catalog.interfaces.IAttributeIndex,
-                    zope.app.catalog.interfaces.ICatalogIndex):
+class IKeywordIndex(zope.catalog.interfaces.IAttributeIndex,
+                    zope.catalog.interfaces.ICatalogIndex):
     """Interface-based catalog keyword index.
     """
 
 
-class KeywordIndex(zope.app.catalog.attribute.AttributeIndex,
+@zope.interface.implementer(IKeywordIndex)
+class KeywordIndex(zope.catalog.attribute.AttributeIndex,
                  zope.index.keyword.KeywordIndex,
                  zope.app.container.contained.Contained):
 
-    zope.interface.implements(IKeywordIndex)
-
+    pass
diff --git a/cybertools/catalog/query.py b/cybertools/catalog/query.py
index 66b77b1..42fc0e3 100644
--- a/cybertools/catalog/query.py
+++ b/cybertools/catalog/query.py
@@ -1,37 +1,18 @@
-#
-#  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
-#  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.catalog.query
 
-"""
-Catalog query terms and their logical combinations.
+""" Catalog query terms and their logical combinations.
 
 This is mainly a simplified version of Martijn Faassen's hurry.query
 (http://cheeseshop.python.org/pypi/hurry.query).
-
-$Id$
 """
 
 from BTrees.IFBTree import weightedIntersection, weightedUnion
 from BTrees.IFBTree import difference, IFBTree, IFBucket, IFSet
 from BTrees.IIBTree import IISet, union
-from zope.app.catalog.catalog import ResultSet
-from zope.app.catalog.field import IFieldIndex
-from zope.app.catalog.text import ITextIndex
-from zope.app.catalog.interfaces import ICatalog
+from zope.catalog.catalog import ResultSet
+from zope.catalog.field import IFieldIndex
+from zope.catalog.text import ITextIndex
+from zope.catalog.interfaces import ICatalog
 from zope import component
 from zope.intid.interfaces import IIntIds
 
@@ -72,7 +53,7 @@ class And(Term):
         if not results:
             # no applicable terms at all
             return IFBucket()
-        results.sort()
+        #results.sort()
         _, result = results.pop(0)
         for _, r in results:
             w, result = weightedIntersection(result, r)
@@ -122,9 +103,8 @@ class Not(Term):
 
 class IndexTerm(Term):
 
-    def __init__(self, (catalog_name, index_name)):
-        self.catalog_name = catalog_name
-        self.index_name = index_name
+    def __init__(self, index_id):
+        self.catalog_name, self.index_name = index_id
 
     def getIndex(self):
         catalog = component.getUtility(ICatalog, self.catalog_name)
diff --git a/cybertools/relation/__init__.py b/cybertools/relation/__init__.py
index 13b445d..d051ec0 100644
--- a/cybertools/relation/__init__.py
+++ b/cybertools/relation/__init__.py
@@ -1,38 +1,19 @@
-# -*- coding: UTF-8 -*-
-# -*- Mode: Python; py-indent-offset: 4 -*-
-#
-#  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
 
-"""
-The relation package provides all you need for setting up dyadic and
+""" The relation package provides all you need for setting up dyadic and
 triadic relations.
 """
 
 from persistent import Persistent
-from zope.interface import implements
-from interfaces import IPredicate
-from interfaces import IRelation, IDyadicRelation, ITriadicRelation
-from interfaces import IRelatable
+from zope.interface import implementer
+from cybertools.relation.interfaces import IPredicate
+from cybertools.relation.interfaces import IRelation, IDyadicRelation, ITriadicRelation
+from cybertools.relation.interfaces import IRelatable
 
+
+@implementer(IPredicate, IRelation)
 class Relation(Persistent):
 
-    implements(IPredicate, IRelation)
-
     order = 0
     relevance = 1.0
     fallback = None
@@ -55,20 +36,18 @@ class Relation(Persistent):
                         'must provide the IRelatable interface.')
 
 
+@implementer(IDyadicRelation)
 class DyadicRelation(Relation):
 
-    implements(IDyadicRelation)
-
     def __init__(self, first, second):
         self.first = first
         self.second = second
         self.checkRelatable(first, second)
 
 
+@implementer(ITriadicRelation)
 class TriadicRelation(Relation):
 
-    implements(ITriadicRelation)
-
     def __init__(self, first, second, third):
         self.first = first
         self.second = second
diff --git a/cybertools/relation/tests.py b/cybertools/relation/tests.py
index aec7e70..22eca20 100755
--- a/cybertools/relation/tests.py
+++ b/cybertools/relation/tests.py
@@ -1,9 +1,9 @@
-# $Id$
+# cybertools.relation.tests
 
 import unittest, doctest
 from zope.app.testing import ztapi
 from zope.interface.verify import verifyClass
-from zope.interface import implements
+from zope.interface import implementer
 from zope.intid.interfaces import IIntIds
 
 from cybertools.relation.interfaces import IDyadicRelation, ITriadicRelation
@@ -12,9 +12,9 @@ from cybertools.relation import Relation, DyadicRelation, TriadicRelation
 from cybertools.relation.interfaces import IRelationRegistry
 
 
+@implementer(IIntIds)
 class IntIdsStub(object):
     """A testing stub (mock utility) for IntIds."""
-    implements(IIntIds)
 
     def __init__(self):
         self.objs = []
@@ -35,7 +35,7 @@ class IntIdsStub(object):
         self.objs[id] = None
 
     def __iter__(self):
-        return iter(xrange(len(self.objs)))
+        return iter(range(len(self.objs)))
 
 
 class TestRelation(unittest.TestCase):
diff --git a/pyproject.toml b/pyproject.toml
index 55ecb6e..5b8dd73 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -21,6 +21,7 @@ dependencies = [
 	"zope.app.testing",
 	"zope.authentication",
 	"zope.browserpage",
+	"zope.catalog",
 	"zope.component",
 	"zope.container",
 	"zope.i18nmessageid",