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4.3 The Requirement Diagram
req [package] Usability requirements [selection]
?«businessRequirement?»
Usage comfort
?«businessRequirement?»
Field of use
?«deriveReqt?»
?«performanceRequirement?»
Response time
reservation system
?«deriveReqt?»
?«requirement?»
Card material
Defi nition
A derive requirement relationship describes that a requirement was derived
from another requirement.
It is a stereotype ?«deriveReqt?» of the UML element abstraction.
Business requirements can result in technical requirements which, in turn, can
lead to other requirements. The derive requirement relationship shows these
relations explicitly. It is permitted only between requirements.
You may already be familiar with the UML ?«derive?» relationship, or with
derived attributes or associations. The term derive is used a lot in UML. To make
sure it is not ??? overstressed, ??? SysML introduces a separate relationship.
The derive requirement relationship is denoted as a dashed arrow with stereotype
?«deriveReqt?» . It is read in direction of the arrowhead, as we read in Figure 4.


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