It is a stereotype ?«probability?» of the UML elements activity edge and parameter
set.
Edges outgoing from a choice have conditions and describe OR semantics. This
means that a token that arrives at a choice node will continue to fl ow over one of
the outgoing edges only where the condition is true.
A probability is a value between zero and one, which describes at each outgoing
edge how probably it is that the token will fl ow over it. You can state the same
at the outgoing edges of an object node, since the OR 10 semantics also applies to
them. The sum of probabilities for all edges of the same origin has to result in 1.
Probability values can also be attached to parameter sets. Different incoming or
outgoing parameter sets have OR semantics.
The probability is denoted at an edge in the following syntax (Figure 4.56):
{probability= < value between 0 and 1 > }
4.9 The State Machine Diagram
The UML state model is used in SysML completely and in unchanged form. The
state machines and the corresponding diagram are independent of the respective
10 To be more exact it is the XOR (exclusive or) semantics.
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