Skip to main content

​
What Is a System Element?

A system element is a Polarion work item of type systemElement that represents a component in the vehicle architecture. Each element has an elementType field from the systemElementType enumeration that places it at a specific level in the hierarchy. The five available element types form a strict containment hierarchy: diagram

​
Element Type Enumeration (systemElementType)

Enum ValueLabelDescription
systemSystemThe top-level product or item under analysis
subsystemSubsystemA major functional grouping within the system
assemblyAssemblyA collection of subassemblies and components
subassemblySubassemblyAn intermediate grouping between assembly and component
componentComponentA leaf-level hardware or software unit

​
Reference Architecture: Connected EV with ADAS

The TARA Demo project models a Connected Electric Vehicle with Advanced Driver Assistance Systems (ADAS). The system element tree is: 
SYSTEM: ADAS Control System (TR-20524)
  +-- SUBSYSTEM: Perception Unit (TR-20525)
  |     +-- COMPONENT: Sensor Fusion ECU (TR-20527)
  |     +-- COMPONENT: Forward Camera Module (TR-21827)
  |     +-- COMPONENT: Front Radar Module (TR-21828)
  +-- SUBSYSTEM: Connectivity Gateway (TR-20526)
        +-- COMPONENT: V2X Transceiver (TR-20528)
        +-- COMPONENT: Telematics Control Unit (TCU) (TR-21829)
This gives 1 system, 2 subsystems, and 5 components (8 system elements total). The hierarchy is stored in the SYSTEM-ELEMENTS document in the _default space. Each TARA module (a riskSpecification document) is scoped to a single system element via the systemElementId document custom field. This field stores the Polarion work item ID of the target element (for example, TR-20527 for the Sensor Fusion ECU).
TARA ModuleSystem ElementElement Type
TARA-ADAS-Control-SystemADAS Control SystemSystem
TARA-Perception-UnitPerception UnitSubsystem
TARA-Sensor-Fusion-ECUSensor Fusion ECUComponent
TARA-Connectivity-GatewayConnectivity GatewaySubsystem
A TARA module is created only for elements that represent distinct attack surfaces. In the reference architecture, the Forward Camera Module, Front Radar Module, V2X Transceiver, and Telematics Control Unit do not have dedicated TARAs — their threats are analyzed as part of their parent subsystem or the system-level TARA.

​
System Element Navigator

The Home dashboard and Risks Home dashboard display the system element tree using an interactive navigator. This two-column table shows each element with its type badge and links to the corresponding TARA module. Elements without a TARA module display a dash. The navigator uses Velocity templates that:
  1. Query all systemElement work items
  2. Traverse parent link roles via linkedWorkItems().back() to build the tree
  3. Match each element to its TARA module using the systemElementId document field

​
ISO/SAE 21434 Context (Clause 9)

The system element hierarchy implements the Item Definition requirement of ISO/SAE 21434 Clause 9. The standard requires defining the item (system under analysis), its boundaries, and its interfaces with other systems. In the TARA solution:
  • The elementType field captures the decomposition level
  • The parent link role captures containment relationships
  • The redAssets document field on each TARA module captures the cybersecurity-relevant assets at each element’s boundary
  • The cybersecurityContext and assumptions document fields capture the security context

​
TARA Coverage and Gap Detection

The TARA Summary Report dashboard automatically detects coverage gaps by comparing the count of system elements against the count of TARA modules. The alert shows: “X system elements | Y TARAs exist | Z TARAs missing.” This coverage check ensures that the analysis team does not inadvertently skip a critical component. The Risks Home dashboard also displays the document workflow status (Draft, In Review, Approved, Published) for each TARA module, enabling project managers to track analysis progress across the hierarchy.

​
See Also