System Upgrade Ontology: A federated ontology for capability sustainment

Sustaining complex engineered systems over decades is not only a data-integration challenge, but a semantic one: upgrade decisions require coherent reasoning across configuration identity, degradation and failure behaviour, temporal evolution, and decision rationale—yet these dimensions are typically modelled in separate tools, with incompatible assumptions about “what a system is over time.” Existing document-centric approaches and many model-based systems engineering/PLM implementations can store artefacts and trace links, but they do not provide the ontological constructs needed to infer, compare, and justify upgrade trajectories (e.g. how a sequence of baselines across epochs produces capability effects under constraints). This paper, therefore, analyses system upgradability as an ontological problem and derives the System Upgrade Ontology (SUO) as a federated semantic solution. SUO operationalises upgradability as a property of configuration trajectories (not isolated components), grounded in rigorous upper-ontology commitments and aligned to enterprise architecture meta-frameworks. It integrates (1) stable representations of system identity and configuration change, (2) imported maintenance/Prognostics and Health Management semantics for degradation and failure, (3) epoch–era temporal structures for long-horizon evolution, and (4) multi-criteria decision factors that make upgrade trade-offs explicit and auditable. A naval combat system case study demonstrates SUO’s explanatory power by showing which upgrade implications are not expressible in operational logistics records alone, and how SUO enables repeatable reasoning over alternative upgrade paths and their multidimensional impacts across service eras.