You must ensure that the constrained element is specified and points to the necessary classifier. Each validation rule modeled as a Constraint has a Constrained Element property. This property determines the type of element this rule applies to. If you create the Constraint for a classifier or stereotype, this property is filled automatically. Otherwise, you need to specify it manually, shown in the following procedure:

To specify a constrained element manually

  1. Open the Constraint Specification window. How to open the Specification window >>
  2. Find the Constrained Element property and select it's value box.

  3. Click Edit and select an appropriate element from the Select Elements dialog.

    For constraints on metaclasses, select an appropriate element from the UML Standard Profile > UML2 Metamodel. Only the single Constrained Element property value is supported for validation rules.

  4. Click OK.
    The Constrained Element property value is specified.