White Paper: One Model

One Model, Many Interests, Many Views

Individual nodes can be expanded or collapsed to show additional relationships or hide additional detail as desired to enhance the communication value of the diagram. When a node is collapsed, a black square is placed in the upper-left corner of the node as an indicator that there are more relationships which have not been shown. When an element occurs multiple times on the same diagram (as with “Workstation” in the sample hierarchy diagram), a black square is frequently placed in the upper-right as a cue to the reader. Because of its classic format and the absence of any specialized symbology, the hierarchy diagram is well-suited for all types of audiences. The information content is intentionally kept low to maintain focus on the interrelationships between system elements – composition, traceability, or both. At its core, the hierarchy diagram represents a generic visual query with no defined semantics. Requirement Diagram The requirement diagram is a SysML extension of the classical hierarchy diagram standardizing the representation of key aspects of requirements – notably decomposition into child requirements and traceability to system elements that satisfy or verify the given requirement. To convey greater information, diagram nodes often show the element description. As a result, requirement diagrams quickly become quite large and therefore are frequently limited to display context for just a handful of requirements. Recognizing this, requirement diagrams are frequently complemented with a tabular representation.

Level of Detail: Medium Audience: System/ software engineers Content: Names, relationships, and descriptions Use: Context for

limited set of requirements

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