UML14 — change trigger

A change trigger specifies an event that occurs when a Boolean-valued expression becomes true as a result of a change in value of one or more attributes or associations." [13.3.8] Does this intend to mean a change in value not of of one or more attributes, but of one or more slots? If so, then does it also intend to mean a change in value not of of one or more associations, but of one or more links? But, can the value of a link change? "A link is a tuple with one value for each end of the assocaition, where each value is an instance of the type of the end." [7.11.2] With a different value, we have a different tuple. Perhaps the text intends: A change trigger specifies an event that occurs when a Boolean-valued expression becomes true as a result of a change in value in one or more slots or the creation of destruction of one or more links.

see above