diff --git a/product/ERP5/Document/TradeModelLineCellConsistencyConstraint.py b/product/ERP5/Document/TradeModelLineCellConsistencyConstraint.py
new file mode 100644
index 0000000000000000000000000000000000000000..0ebd35ee4bb5c09410db9917ffbc4b8f77fb8d29
--- /dev/null
+++ b/product/ERP5/Document/TradeModelLineCellConsistencyConstraint.py
@@ -0,0 +1,64 @@
+##############################################################################
+#
+# Copyright (c) 2009-2010 Nexedi SA and Contributors. All Rights Reserved.
+#                         Fabien Morin <fabien@nexedi.com>
+#                         Arnaud Fontaine <arnaud.fontaine@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# 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.
+#
+##############################################################################
+
+from Products.ERP5Type.mixin.constraint import ConstraintMixin
+from Products.ERP5Type import PropertySheet
+
+class TradeModelLineCellConsistencyConstraint(ConstraintMixin):
+  """
+  This constraint checks if the Trade Model Line should contain cells (if
+  variation categories are defined on it)
+
+  This is only relevant for ZODB Property Sheets (filesystem Property
+  Sheets rely on Products.ERP5.Constraint.TradeModelLineCellConsistency
+  instead).
+  """
+  meta_type = 'ERP5 Trade Model Line Cell Consistency Constraint'
+  portal_type = 'Trade Model Line Cell Consistency Constraint'
+
+  property_sheets = (PropertySheet.SimpleItem,
+                     PropertySheet.Predicate,
+                     PropertySheet.Reference,
+                     PropertySheet.TradeModelLineCellConsistencyConstraint)
+
+  def checkConsistency(self, document, fixit=0):
+    """
+    Check the object's consistency
+    """
+    if not self.test(document):
+      return []
+
+    base_id = self.getBaseId()
+    for cell_coordinates in document.getCellKeyList(base_id=base_id):
+      if document.getCell(base_id=base_id, *cell_coordinates) is None:
+        return [self._generateError(
+          document, self._getMessage('message_cell_inexistance'),
+          mapping=dict(line=document.getTitle()))]
+
+    return []
diff --git a/product/ERP5/PropertySheet/TradeModelLineCellConsistencyConstraint.py b/product/ERP5/PropertySheet/TradeModelLineCellConsistencyConstraint.py
new file mode 100644
index 0000000000000000000000000000000000000000..d06f0f7352d5bab769b5983d7e1db8c5e5b48793
--- /dev/null
+++ b/product/ERP5/PropertySheet/TradeModelLineCellConsistencyConstraint.py
@@ -0,0 +1,43 @@
+##############################################################################
+#
+# Copyright (c) 2010 Nexedi SARL and Contributors. All Rights Reserved.
+#                    Arnaud Fontaine <arnaud.fontaine@nexedi.com>
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# 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.
+#
+##############################################################################
+
+class TradeModelLineCellConsistencyConstraint:
+    """
+    Define an Trade Model Line Cell Consistency Constraint for ZODB
+    Property Sheets
+    """
+    _properties = (
+        {   'id': 'base_id',
+            'type': 'string',
+            'description' : 'Cell base_id' },
+        {   'id': 'message_cell_inexistance',
+            'type': 'string',
+            'description' : 'Error message when there is a missing cell for '\
+                            'a given line',
+            'default': 'Missing cells on line "${line}"' },
+        )