Partially Ordered Dependencies
LOW MODERATE HIGHRequirements NIST SOURCE
Implement the security design principle of partially ordered dependencies in [systems or system components].
Discussion (NIST Supplemental Guidance)
The principle of partially ordered dependencies states that the synchronization, calling, and other dependencies in the system are partially ordered. A fundamental concept in system design is layering, whereby the system is organized into well-defined, functionally related modules or components. The layers are linearly ordered with respect to inter-layer dependencies, such that higher layers are dependent on lower layers. While providing functionality to higher layers, some layers can be self-contained and not dependent on lower layers. While a partial ordering of all functions in a given system may not be possible, if circular dependencies are constrained to occur within layers, the inherent problems of circularity can be more easily managed. Partially ordered dependencies and system layering contribute significantly to the simplicity and coherency of the system design. Partially ordered dependencies also facilitate system testing and analysis.
Implementation Guidance
Original engineering commentary written for this explorer — not NIST source text and not authoritative guidance.
No engineering interpretation has been authored for SA-8(4) yet. This section is architected to receive it — see the Requirements and Assessment sections above for the authoritative NIST source content in the meantime.
Assessment
Assessment Objectives
- systems or system components that implement the security design principle of partially ordered dependencies are defined;
- <SA-08(04)_ODP systems or system components> implement the security design principle of partially ordered dependencies.
Examine
[SELECT FROM: System and services acquisition policy; procedures addressing the security design principle of partially ordered dependencies used in the specification, design, development, implementation, and modification of the system; system design documentation; security and privacy requirements and specifications for the system; system security and privacy architecture; system security plan; other relevant documents or records].
Interview
[SELECT FROM: Organizational personnel with the responsibility for determining system security and privacy requirements; organizational personnel with system specification, design, development, implementation, and modification responsibilities; system developers; organizational personnel with information security responsibilities].
Test
[SELECT FROM: Organizational processes for applying the security design principle of partially ordered dependencies in system specification, design, development, implementation, and modification; mechanisms supporting the application of the security design principle of partially ordered dependencies in system specification, design, development, implementation, and modification].
Overlays
STIGs & CCIs
No STIG checks or CCI mappings are currently loaded for SA-8(4). This section is architected to display, per product: STIG ID, Finding ID, Severity, Title, Description, Check, Fix, CCI, and NIST control mapping — but nothing is populated here until a real DISA STIG/CCI dataset is ingested.
Learn more about STIG/CCI integration →Evidence
Categorized from the SP 800-53A "Examine"/"Test" artifact list above by keyword — not an authoritative NIST evidence list.
Policy
- System and services acquisition policy
- system security plan
Configuration
- system design documentation
- system security and privacy architecture
Testing
- Organizational processes for applying the security design principle of partially ordered dependencies in system specification, design, development, implementation, and modification
- mechanisms supporting the application of the security design principle of partially ordered dependencies in system specification, design, development, implementation, and modification
Other Records
- procedures addressing the security design principle of partially ordered dependencies used in the specification, design, development, implementation, and modification of the system
- security and privacy requirements and specifications for the system
- other relevant documents or records