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The state Day stands
for all value combinations of the attributes hour , minute , and second , between
the two events, sunrise and sunset. 16 This example shows clearly that a state is
an abstraction of possible value combinations. Not every value combination is a
meaningful state, for example, the state ??? 13:17:31 ??? (HH:MM:SS), which is not modeled
here. What is meaningful and what isn ??™ t eventually depends on the domain
we model, of course.
States are represented by rounded rectangles ( Figure 3.57 ). The name of the
state is within the rectangle. Another compartment shows the internal behavior,
which is triggered by events, similar to transitions, but which does not cause the
state to be exited.
194 CHAPTER 3 UML??”Unifi ed Modeling Language
In addition to the internal behavior, a state can also have three special behaviors
that are triggered on the basis of predefi ned events:
?–  The entry behavior is executed immediately upon entering the state.
?–  The exit behavior is executed immediately before exiting the state.


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