diff --git a/cybertools/commerce/README.txt b/cybertools/commerce/README.txt
index 9c38be5..fd0e666 100644
--- a/cybertools/commerce/README.txt
+++ b/cybertools/commerce/README.txt
@@ -15,18 +15,18 @@ Shops and Products
 
 Let's start with two shops:
 
-  >>> shop1 = manager.shops.create(u'shop1', title=u'PC up Ltd')
-  >>> shop2 = manager.shops.create(u'shop2', title=u'Video up Ltd')
+  >>> shop1 = manager.shops.create('shop1', title='PC up Ltd')
+  >>> shop2 = manager.shops.create('shop2', title='Video up Ltd')
 
   >>> len(list(manager.shops))
   2
 
 Now we add products to the shops.
 
-  >>> p001 = manager.products.create(u'001', title=u'Silent Case')
-  >>> p002 = manager.products.create(u'002', title=u'Portable Projector')
-  >>> p003 = manager.products.create(u'003', title=u'HD Flatscreen Monitor')
-  >>> p004 = manager.products.create(u'004', title=u'Giga Mainboard')
+  >>> p001 = manager.products.create('001', title='Silent Case')
+  >>> p002 = manager.products.create('002', title='Portable Projector')
+  >>> p003 = manager.products.create('003', title='HD Flatscreen Monitor')
+  >>> p004 = manager.products.create('004', title='Giga Mainboard')
 
   >>> shop1.products.add(p001)
   >>> shop1.products.add(p003)
@@ -35,30 +35,30 @@ Now we add products to the shops.
   >>> shop2.products.add(p003)
 
   >>> sorted((p.productId, p.title) for p in shop1.products)
-  [(u'001', u'Silent Case'), (u'003', u'HD Flatscreen Monitor'),
-   (u'004', u'Giga Mainboard')]
+  [('001', 'Silent Case'), ('003', 'HD Flatscreen Monitor'),
+   ('004', 'Giga Mainboard')]
 
 Let's have a look at the product - it should correctly reference the shops
 it belongs to.
 
   >>> sorted((s.name, s.title) for s in p003.shops)
-  [(u'shop1', u'PC up Ltd'), (u'shop2', u'Video up Ltd')]
+  [('shop1', 'PC up Ltd'), ('shop2', 'Video up Ltd')]
 
 We can also create a manufacturer and set it for a product.
 
-  >>> mf001 = manager.manufacturers.create(u'001', title=u'Global Electronics')
+  >>> mf001 = manager.manufacturers.create('001', title='Global Electronics')
   >>> p001.manufacturer = mf001
   >>> [p.title for p in mf001.products]
-  [u'Silent Case']
+  ['Silent Case']
 
 
 Customers
 =========
 
-  >>> c001 = manager.customers.create(u'001', title=u'Your Local Computer Store')
-  >>> c002 = manager.customers.create(u'002', title=u'Speedy Gonzales')
-  >>> c003 = manager.customers.create(u'003', title=u'TeeVee')
-  >>> c004 = manager.customers.create(u'004', title=u'MacVideo')
+  >>> c001 = manager.customers.create('001', title='Your Local Computer Store')
+  >>> c002 = manager.customers.create('002', title='Speedy Gonzales')
+  >>> c003 = manager.customers.create('003', title='TeeVee')
+  >>> c004 = manager.customers.create('004', title='MacVideo')
 
   >>> shop1.customers.add(c001)
   >>> shop1.customers.add(c002)
@@ -68,11 +68,11 @@ Customers
   >>> shop2.customers.add(c004)
 
   >>> sorted((c.customerId, c.title) for c in shop1.customers)
-  [(u'001', u'Your Local Computer Store'), (u'002', u'Speedy Gonzales'),
-   (u'004', u'MacVideo')]
+  [('001', 'Your Local Computer Store'), ('002', 'Speedy Gonzales'),
+   ('004', 'MacVideo')]
 
   >>> sorted((s.name, s.title) for s in c002.shops)
-  [(u'shop1', u'PC up Ltd'), (u'shop2', u'Video up Ltd')]
+  [('shop1', 'PC up Ltd'), ('shop2', 'Video up Ltd')]
 
 
 Carts and Orders
@@ -84,16 +84,16 @@ A cart is just a collection of order items belonging to a certain customer
   >>> orderItems = manager.orderItems
 
   >>> orderItems.add(p001, c001, shop=shop1, quantity=3)
-  <OrderItem [2, 1, 7, '... ...', '???']: {'shop': 0, 'quantity': 3}>
+  <OrderItem [2, 1, 7, '... ...', -1]: {'quantity': 3, 'shop': 0}>
 
   >>> orderItems.getCart(c001)
-  [<OrderItem [2, 1, 7, '... ...', '???']: {'shop': 0, 'quantity': 3}>]
+  [<OrderItem [2, 1, 7, '... ...', -1]: {'quantity': 3, 'shop': 0}>]
   >>> item1 = orderItems.getCart(c001, shop=shop1, product=p001)[0]
   >>> item1
-  <OrderItem [2, 1, 7, '... ...', '???']: {'shop': 0, 'quantity': 3}>
+  <OrderItem [2, 1, 7, '... ...', -1]: {'quantity': 3, 'shop': 0}>
 
   >>> orderItems.add(p003, c001, shop=shop1, quantity=1)
-  <OrderItem [4, 2, 7, '... ...', '???']: {'shop': 0, 'quantity': 1}>
+  <OrderItem [4, 2, 7, '... ...', -1]: {'quantity': 1, 'shop': 0}>
 
   >>> len(orderItems.getCart(c001))
   2
@@ -102,7 +102,7 @@ If we add the same product again to the cart no new item is created but
 the quantity is added to the existing item.
 
   >>> orderItems.add(p003, c001, shop=shop1, quantity=1)
-  <OrderItem [4, 2, 7, '... ...', '???']: {'shop': 0, 'quantity': 2}>
+  <OrderItem [4, 2, 7, '... ...', -1]: {'quantity': 2, 'shop': 0}>
   >>> len(orderItems.getCart(c001))
   2
 
@@ -127,4 +127,4 @@ retrieving the order items.
   >>> orderItems.getCart(c001)
   []
   >>> orderItems.getCart(c001, ord001)
-  [<OrderItem [4, 2, 7, '... ...', 11]: {'shop': 0, 'quantity': 2}>]
+  [<OrderItem [4, 2, 7, '... ...', 11]: {'quantity': 2, 'shop': 0}>]
diff --git a/cybertools/commerce/customer.py b/cybertools/commerce/customer.py
index 00aa0af..6466b28 100644
--- a/cybertools/commerce/customer.py
+++ b/cybertools/commerce/customer.py
@@ -1,37 +1,17 @@
-#
-#  Copyright (c) 2009 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.commerce.customer
 
-"""
-Customer classes.
-
-$Id$
+""" Customer classes.
 """
 
-from zope.interface import implements, Interface
+from zope.interface import implementer, Interface
 
 from cybertools.commerce.common import RelationSet, BaseObject
 from cybertools.commerce.interfaces import ICustomer, IAddress
 
 
+@implementer(ICustomer)
 class Customer(BaseObject):
 
-    implements(ICustomer)
-
     def __init__(self, customerId, title=None, client=None):
         self.name = self.customerId = customerId
         self.title = title or u'unknown'
@@ -40,7 +20,8 @@ class Customer(BaseObject):
         self.orders = self.collection(self, 'customer')
 
 
+@implementer(IAddress)
 class Address(BaseObject):
 
-    implements(IAddress)
+    pass
 
diff --git a/cybertools/commerce/manager.py b/cybertools/commerce/manager.py
index 26fac27..b7094fc 100644
--- a/cybertools/commerce/manager.py
+++ b/cybertools/commerce/manager.py
@@ -1,28 +1,9 @@
-#
-#  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.commerce.manager
 
-"""
-The commerce manager (container, registry, ...).
-
-$Id$
+""" The commerce manager (container, registry, ...).
 """
 
-from zope.interface import implements
+from zope.interface import implementer
 
 from cybertools.commerce.common import ContainerAttribute
 from cybertools.commerce.customer import Customer
@@ -33,10 +14,9 @@ from cybertools.commerce.shop import Shop
 from cybertools.tracking.btree import TrackingStorage
 
 
+@implementer(IManager)
 class Manager(object):
 
-    implements(IManager)
-
     def __init__(self):
         self.shops = ContainerAttribute(Shop)
         self.products = ContainerAttribute(Product, 'productId')
diff --git a/cybertools/commerce/order.py b/cybertools/commerce/order.py
index 14e180e..09173e4 100644
--- a/cybertools/commerce/order.py
+++ b/cybertools/commerce/order.py
@@ -1,20 +1,4 @@
-#
-#  Copyright (c) 2015 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.commerce.order
 
 """
 Order and order item classes.
@@ -23,7 +7,7 @@ Order and order item classes.
 from zope.cachedescriptors.property import Lazy
 from zope import component
 from zope.component import adapts
-from zope.interface import implements, Interface
+from zope.interface import implementer, Interface
 from zope.intid.interfaces import IIntIds
 
 from cybertools.commerce.common import getUidForObject, getObjectForUid
@@ -33,10 +17,9 @@ from cybertools.tracking.btree import Track
 from cybertools.tracking.interfaces import ITrackingStorage
 
 
+@implementer(IOrder)
 class Order(BaseObject):
 
-    implements(IOrder)
-
     customer = Relation('_customer', 'orders')
 
     def __init__(self, orderId, shop=None, customer=None):
@@ -45,10 +28,9 @@ class Order(BaseObject):
         self.customer = customer
 
 
+@implementer(IOrderItem)
 class OrderItem(Track):
 
-    implements(IOrderItem)
-
     metadata_attributes = Track.metadata_attributes + ('order',)
     index_attributes = metadata_attributes
     typeName = 'OrderItem'
@@ -85,11 +67,11 @@ class OrderItem(Track):
         parent.context.indexTrack(0, self, 'order')
 
 
+@implementer(IOrderItems)
 class OrderItems(object):
     """ A tracking storage adapter managing order items.
     """
 
-    implements(IOrderItems)
     adapts(ITrackingStorage)
 
     def __init__(self, context):
@@ -114,7 +96,7 @@ class OrderItems(object):
             criteria['runId'] = criteria.pop('run')
         return self.context.query(**criteria)
 
-    def add(self, product, party, shop, order='???', run=0, **kw):
+    def add(self, product, party, shop, order=-1, run=0, **kw):
         kw['shop'] = self.getUid(shop)
         existing = self.getCart(party, order, shop, run, product=product)
         options = kw.get('options')
@@ -132,7 +114,7 @@ class OrderItems(object):
             self.context.indexTrack(0, track, 'order')
         return track
 
-    def getCart(self, party=None, order='???', shop=None, run=None, **kw):
+    def getCart(self, party=None, order=-1, shop=None, run=None, **kw):
         if run:
             kw['run'] = run
         result = self.query(party=party, order=order, **kw)
diff --git a/cybertools/commerce/product.py b/cybertools/commerce/product.py
index fd5281e..542e809 100644
--- a/cybertools/commerce/product.py
+++ b/cybertools/commerce/product.py
@@ -1,38 +1,18 @@
-#
-#  Copyright (c) 2009 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.commerce.product
 
-"""
-Product classes.
-
-$Id$
+""" Product classes.
 """
 
-from zope.interface import implements, Interface
+from zope.interface import implementer, Interface
 
 from cybertools.commerce.common import Relation, RelationSet, BaseObject
 from cybertools.commerce.interfaces import IProduct, ICategory
 from cybertools.commerce.interfaces import IManufacturer, ISupplier
 
 
+@implementer(IProduct)
 class Product(BaseObject):
 
-    implements(IProduct)
-
     manufacturer = Relation('_manufacturer', 'products')
 
     def __init__(self, productId, title=None):
@@ -44,10 +24,9 @@ class Product(BaseObject):
         self.suppliers = self.collection(self, 'products')
 
 
+@implementer(ICategory)
 class Category(BaseObject):
 
-    implements(ICategory)
-
     def __init__(self, name, title=None):
         self.name = name
         self.title = title or u'unknown'
@@ -58,20 +37,18 @@ class Category(BaseObject):
         self.parentCategories = self.collection(self, 'subCategories')
 
 
+@implementer(IManufacturer)
 class Manufacturer(BaseObject):
 
-    implements(IManufacturer)
-
     def __init__(self, name, title=None):
         self.name = name
         self.title = title or u'unknown'
         self.products = self.collection(self, 'manufacturer')
 
 
+@implementer(ISupplier)
 class Supplier(BaseObject):
 
-    implements(ISupplier)
-
     def __init__(self, name, title=None):
         self.name = name
         self.title = title or u'unknown'
diff --git a/cybertools/commerce/shop.py b/cybertools/commerce/shop.py
index 98afa61..b152446 100644
--- a/cybertools/commerce/shop.py
+++ b/cybertools/commerce/shop.py
@@ -1,37 +1,17 @@
-#
-#  Copyright (c) 2009 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.commerce.shop
 
-"""
-Base classes.
-
-$Id$
+""" Base classes.
 """
 
-from zope.interface import implements
+from zope.interface import implementer
 
 from cybertools.commerce.common import RelationSet, BaseObject
 from cybertools.commerce.interfaces import IShop
 
 
+@implementer(IShop)
 class Shop(BaseObject):
 
-    implements(IShop)
-
     collection = RelationSet
 
     def __init__(self, name, title=None):
diff --git a/cybertools/commerce/tests.py b/cybertools/commerce/tests.py
index 4dfaa1e..53bb80e 100755
--- a/cybertools/commerce/tests.py
+++ b/cybertools/commerce/tests.py
@@ -7,16 +7,16 @@ Tests for the 'cybertools.commerce' package.
 import unittest, doctest
 
 from zope import component
-from zope.interface import implements
+from zope.interface import implementer
 from zope.intid.interfaces import IIntIds
 
 from cybertools.commerce.order import OrderItems
 from cybertools.commerce.product import Product
 
 
+@implementer(IIntIds)
 class IntIdsStub(object):
     """A testing stub (mock utility) for IntIds."""
-    implements(IIntIds)
 
     def __init__(self):
         self.objs = []
@@ -37,7 +37,7 @@ class IntIdsStub(object):
         self.objs[id] = None
 
     def __iter__(self):
-        return iter(xrange(len(self.objs)))
+        return iter(range(len(self.objs)))
 
 
 def setUp(testCase):
diff --git a/cybertools/composer/base.py b/cybertools/composer/base.py
index d9151e7..cd2ca1c 100644
--- a/cybertools/composer/base.py
+++ b/cybertools/composer/base.py
@@ -1,58 +1,39 @@
-#
-#  Copyright (c) 2007 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.composer.base
 
-"""
-Basic classes for complex template structures.
-
-$Id$
+""" Basic classes for complex template structures.
 """
 
-from zope.interface import implements
+from zope.interface import implementer
 
 from cybertools.composer.interfaces import IComponent, IElement, ICompound
 from cybertools.composer.interfaces import ITemplate
 from cybertools.util.jeep import Jeep
 
 
+@implementer(IComponent)
 class Component(object):
 
-    implements(IComponent)
+    pass
 
 
+@implementer(IElement)
 class Element(Component):
 
-    implements(IElement)
+    pass
 
 
+@implementer(ICompound)
 class Compound(Component):
 
-    implements(ICompound)
-
     componentStorage = Jeep
 
     def __init__(self):
         self.parts = self.componentStorage()
 
 
+@implementer(ITemplate)
 class Template(object):
 
-    implements(ITemplate)
-
     componentStorage = Jeep
     components = None
 
diff --git a/cybertools/composer/schema/factory.py b/cybertools/composer/schema/factory.py
index 91dddbc..d4cf32e 100644
--- a/cybertools/composer/schema/factory.py
+++ b/cybertools/composer/schema/factory.py
@@ -1,27 +1,10 @@
-#
-#  Copyright (c) 2016 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.composer.schema.factory
 
-"""
-Schema factory stuff.
+""" Schema factory stuff.
 """
 
 from zope.component import adapts
-from zope.interface import implements
+from zope.interface import implementer
 from zope.interface import Interface
 from zope import schema
 
@@ -43,12 +26,12 @@ schema.Float.__typeInfo__ = ('decimal',)
 schema.Choice.__typeInfo__ = ('dropdown',)
 
 
+@implementer(ISchemaFactory)
 class SchemaFactory(object):
     """ Creates a cybertools.composer schema from an
         interface (a zope.schema schema).
     """
 
-    implements(ISchemaFactory)
     adapts(Interface)
 
     fieldMapping = {
diff --git a/cybertools/composer/schema/field.py b/cybertools/composer/schema/field.py
index 578e984..de1c135 100644
--- a/cybertools/composer/schema/field.py
+++ b/cybertools/composer/schema/field.py
@@ -1,31 +1,14 @@
-#
-#  Copyright (c) 2016 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.composer.schema.field
 
-"""
-Schema fields and related classes.
+""" Schema fields and related classes.
 """
 
 from datetime import datetime
 from logging import getLogger
 from time import strptime, strftime
-from zope.app.form.browser.interfaces import ITerms
+from zope.browser.interfaces import ITerms
 from zope.i18n.locales import locales
-from zope.interface import implements
+from zope.interface import implementer
 from zope.cachedescriptors.property import Lazy
 from zope.component import adapts
 from zope import component
@@ -50,10 +33,9 @@ class FieldGroup(object):
         self.sublabels = sublabels
 
 
+@implementer(IField)
 class Field(Component):
 
-    implements(IField)
-
     visible = True
     required = False
     readonly = False
@@ -104,7 +86,7 @@ class Field(Component):
             ctx = Context(Engine, self.getContextProperties())
             try:
                 return expr(ctx)
-            except AttributeError, KeyError:
+            except (AttributeError, KeyError):
                 return u''
         return self.default
     def setDefaultValue(self, value):
@@ -190,9 +172,9 @@ class Field(Component):
         return dict(context=self, user=None)
 
 
+@implementer(IFieldInstance)
 class FieldInstance(object):
 
-    implements(IFieldInstance)
     adapts(IField)
 
     clientInstance = None
@@ -361,7 +343,7 @@ class DateFieldInstance(NumberFieldInstance):
                         'DateFieldInstance: year out of range: %s, %s' % 
                             (value, e))
                     self.setError('invalid_datetime')
-            except (TypeError, ValueError, DateTimeParseError), e:
+            except ((TypeError, ValueError, DateTimeParseError), e):
                 getLogger('cybertools').warn(
                         'DateFieldInstance: invalid datetime: %s, %s' % (value, e))
                 self.setError('invalid_datetime')
diff --git a/cybertools/composer/schema/schema.py b/cybertools/composer/schema/schema.py
index 92f50e0..fa73603 100644
--- a/cybertools/composer/schema/schema.py
+++ b/cybertools/composer/schema/schema.py
@@ -1,27 +1,10 @@
-#
-#  Copyright (c) 2014 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.composer.schema.schema
 
-"""
-Basic classes for schemas, i.e. sets of fields that may be used for creating
+""" Basic classes for schemas, i.e. sets of fields that may be used for creating
 editing forms or display views for objects.
 """
 
-from zope.interface import implements
+from zope.interface import implementer
 
 from cybertools.composer.base import Component, Element, Compound
 from cybertools.composer.base import Template
@@ -29,10 +12,9 @@ from cybertools.composer.schema.interfaces import ISchema, IFormState
 from cybertools.util.jeep import Jeep
 
 
+@implementer(ISchema)
 class Schema(Template):
 
-    implements(ISchema)
-
     name = u''
     labelWidth = 'auto'
     manager = None
@@ -63,10 +45,9 @@ class Schema(Template):
         return self.manager
 
 
+@implementer(IFormState)
 class FormState(object):
 
-    implements(IFormState)
-
     def __init__(self, fieldInstances=None, changed=False, severity=0):
         if fieldInstances is None:
             fieldInstances = []
diff --git a/pyproject.toml b/pyproject.toml
index 5b8dd73..2ddbefa 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,10 +20,12 @@ dependencies = [
 	"zope.app.rotterdam",
 	"zope.app.testing",
 	"zope.authentication",
+	"zope.browser",
 	"zope.browserpage",
 	"zope.catalog",
 	"zope.component",
 	"zope.container",
+	"zope.formlib",
 	"zope.i18nmessageid",
 	"zope.index",
 	"zope.interface",