UML14 — Action should be concrete

Action should be concrete. The description of the "effect" attribute
says: "An optional text specification of the effect of the action. This
may be used to indicate the behavior of an action without specialization
into a subclass, ... " We think this is a good concept, and would like
to instantiate Action for activity nodes whose behavior is only verbally
described. Behavior, too.

In Figure 176, make Action concrete.