UML22 — constrainedElement direction

constrainedElement direction The association between Constraint and Element named "constrainedElement" is unidirectional from Constraint to Element. This means implementations are not required to provide efficient navigation from an element to the constraints on it. Since the constraints of a model element are part of the definition of that element, the required navigation should at least be from the element to the constraint.

Discussion
A Constraint can constrain multiple constrainedElements and, thus, is not necessarily owned by any one of them. In
this sense, the Constraint is not, in general, part of the formal “definition” of the constrainedElements. Rather, if
the Constraint has a context (which may or may not be a constrainedElement), then it is more proper to think of the
constraint as part of the definition of that context, and the context association end is navigable.
Further, one wants to be able to add constraints to elements of the model without having tomodify an owned property
of the elements being constrained, but making the association from Element to Constraint would imply (by the usual
UML abstract syntax metamodel conventions) that the “constraint” association end would become owned by Element.
Disposition: Closed - No Change