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17 ).
4.3.9 Trace Relationship
Defi nition
A trace relationship is a relationship between a requirement and an arbitrary
model element; it describes a general relation for traceability reasons only.
It is a standard stereotype ?«trace?» of the UML abstraction relationship.
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The trace relationship is very general, and its semantics is accordingly weak. It
expresses that the model elements have a relationship without specifying this
relationship in more detail. The sole purpose of a trace relationship is to create
traceability between elements. It does not state why there is a relation.
SysML takes this relationship unchanged from UML, but it adds an alternative
notation, similarly to using a comment symbol ( Figure 4.17 ) for the refi ne relationship.
In this case, it uses the keywords TracedTo and TracedFrom . This alternative
notation is useful especially when the participating model elements should not or
cannot appear in a diagram.
You can see an example for trace in Figure 4.18 . In this example, the usability
concept is related to the display size.


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