diff --git a/commerce/README.txt b/commerce/README.txt
index 7199863..9232e57 100644
--- a/commerce/README.txt
+++ b/commerce/README.txt
@@ -1,14 +1,41 @@
-==========================================
-Commerce: Products, Customers, Orders, ...
-==========================================
+=================================================
+Commerce: Shope, Products, Customers, Orders, ...
+=================================================
 
   ($Id$)
 
 
-Products
-========
+Shops and Products
+==================
 
-Let's start with a Product:
+Let's start with a Shop:
+
+  >>> from cybertools.commerce.base import Shop
+  >>> shop1 = Shop(u'shop1', u'PC up Ltd')
+
+Now we add products to the shop.
 
   >>> from cybertools.commerce.product import Product
-  >>> p1 = Product()
+  >>> p001 = Product(u'p001', u'Silent Case')
+
+  >>> shop1.addProduct(p001)
+
+  >>> sorted((name, p.title) for name, p in shop1.products.items())
+  [(u'p001', u'Silent Case')]
+
+Let's have a look at the product - it should correctly reference the shop
+it belongs to.
+
+  >>> len(p001.shops)
+  1
+  >>> p001.shops.keys()[0]
+  u'shop1'
+
+
+Customers
+=========
+
+
+Orders
+======
+
diff --git a/commerce/base.py b/commerce/base.py
new file mode 100644
index 0000000..08ee9d7
--- /dev/null
+++ b/commerce/base.py
@@ -0,0 +1,44 @@
+#
+#  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
+#
+
+"""
+Base classes.
+
+$Id$
+"""
+
+from zope.interface import implements, Interface
+
+from cybertools.commerce.interfaces import IShop
+
+
+class Shop(object):
+
+    implements(IShop)
+
+    title = u'Shop'
+
+    def __init__(self, name, title=None):
+        self.name = name
+        if title is not None:
+            self.title = title
+        self.products = {}
+
+    def addProduct(self, product):
+        self.products[product.name] = product
+        product.shops[self.name] = self
diff --git a/commerce/interfaces.py b/commerce/interfaces.py
index af446f0..0c10c46 100644
--- a/commerce/interfaces.py
+++ b/commerce/interfaces.py
@@ -61,6 +61,10 @@ class IShop(Interface):
                     u'this shop.')
     customers = Attribute(u'The customers registered for this shop.')
 
+    def addProduct(product):
+        """ Add the product given to the shop's product listing.
+        """
+
 
 # suppliers
 
@@ -98,8 +102,7 @@ class IProduct(Interface):
 
     productId = schema.ASCIILine(
             title=_(u'Product Identifier'),
-            description=_(u'A name or number uniquely identifiying the '
-                    u'product within a shop.'),
+            description=_(u'A name or number uniquely identifiying the product.'),
             default='',
             required=True)
     title = schema.TextLine(
diff --git a/commerce/locales/de/LC_MESSAGES/cybertools.commerce.mo b/commerce/locales/de/LC_MESSAGES/cybertools.commerce.mo
index bbbb2e1..d2d8e7d 100644
Binary files a/commerce/locales/de/LC_MESSAGES/cybertools.commerce.mo and b/commerce/locales/de/LC_MESSAGES/cybertools.commerce.mo differ
diff --git a/commerce/locales/de/LC_MESSAGES/cybertools.commerce.po b/commerce/locales/de/LC_MESSAGES/cybertools.commerce.po
index 1a46387..9bdbf36 100644
--- a/commerce/locales/de/LC_MESSAGES/cybertools.commerce.po
+++ b/commerce/locales/de/LC_MESSAGES/cybertools.commerce.po
@@ -17,8 +17,8 @@ msgstr "Artikel"
 msgid "Product Identifier"
 msgstr "Artikelnummer"
 
-msgid "A name or number uniquely identifiying the product within a shop."
-msgstr "Kurzbezeichnung oder Nummer, die den Artikel innerhalb eines Shops eindeutig identifiziert."
+msgid "A name or number uniquely identifiying the product."
+msgstr "Kurzbezeichnung oder Nummer, die den Artikel eindeutig identifiziert."
 
 msgid "Product Name"
 msgstr "Artikelbezeichnung"
diff --git a/commerce/product.py b/commerce/product.py
index 24458f0..cfa8a5c 100644
--- a/commerce/product.py
+++ b/commerce/product.py
@@ -31,3 +31,11 @@ class Product(object):
 
     implements(IProduct)
 
+    title = u'Product'
+
+    def __init__(self, name, title=None):
+        self.name = name
+        if title is not None:
+            self.title = title
+        self.shops = {}
+
diff --git a/commerce/tests.py b/commerce/tests.py
index 7496228..85ce6d1 100755
--- a/commerce/tests.py
+++ b/commerce/tests.py
@@ -14,7 +14,7 @@ class Test(unittest.TestCase):
     "Basic tests."
 
     def testBasicStuff(self):
-        p = Product()
+        p = Product('p001')
 
 
 def test_suite():