diff --git a/product/ERP5Type/Constraint/PropertyExistence.py b/product/ERP5Type/Constraint/PropertyExistence.py
new file mode 100755
index 0000000000000000000000000000000000000000..cfbd42c2f1c9f5ab477b3e7432462f526339b7a1
--- /dev/null
+++ b/product/ERP5Type/Constraint/PropertyExistence.py
@@ -0,0 +1,68 @@
+##############################################################################
+#
+# Copyright (c) 2002 Nexedi SARL and Contributors. All Rights Reserved.
+#                    Sebastien Robin <seb@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 Constraint import Constraint
+
+class PropertyExistence(Constraint):
+    """
+    This method check and fix if an object respects the existence of a property.
+
+    For example we can check if every invoice line has a price defined on it.
+    """
+
+    def __init__(self, **constraint_definition):
+      """
+        We need the definition list of the constraint
+      """
+      self.constraint_definition = constraint_definition
+
+    def checkConsistency(self, object, fixit = 0):
+      """
+        this is the check method, we return a list of string,
+        each string corresponds to an error.
+      """
+
+      errors = []
+
+      # Retrieve values inside de PropertySheet (_constraints)
+      property_id = self.constraint_definition['property_id']
+
+      # Check arity and compare it with the min and max
+      error_message = None
+      if not self.hasProperty(property_id):
+          error_message = "Property existence error for property '%s': " % property_id  \
+                + " this document has no such property"
+      elif self.getProperty(property_id) is None:
+          error_message = "Property existence error for property '%s': " % property_id  \
+                + " this property was not defined"
+      if error_message:
+        errors = [(object.getRelativeUrl(), 'CategoryMembershipArity inconsistency',104, error_message)]
+      else:
+        errors = []
+        
+      return errors