This report examines the use of higraphs as a means of representing dependencies and relationships among multiple aspects of system development models (e.g., requirements, hardware, software, testing concerns). We show how some well-known diagram types in UML have counterpart higraph representations, how these models incorporate hierarchy and orthogonality, and how each model can be connected to the others in a useful (and formal) manner. Present-day visual modeling languages such as UML and SysML do not readily support: (1) The traceability mechanisms required for the tracking of requirements changes, and (2) Builtin support for systems validation. Higraphs also deviate from UML and SysML in their ability to model requirements, rules, and domain knowledge relevant to the development of models for system behavior and system structure. To accommodate these demands, an extension to the basic mathematical definition of higraphs is proposed. Capabilities of the extended higraph model are examined through model development for an office network computing system.