Abstract
Industrial CAD/STEP models provide high-fidelity geometry and product structure, yet automated assembly/disassembly planning also requires machine-interpretable semantics about how parts are connected (e.g., fastening, retention, kinematic guidance) and which operations must precede others. We present an ontology design pattern grounded in DOLCE+DnS Ultralite (DUL) that represents each assembly connection as a reified joint situation, annotated with STEP-derived interface geometry, and optional descriptors such as retention method and degrees of freedom. From these structured connection descriptions, we derive a connection-aware precedence matrix. Hard (MUST) constraints are validated by geometric feasibility checks, while soft (DEFAULT) precedence candidates are generated by reusable templates over joint descriptors and can be overridden when evidence conflicts. A gearbox case study illustrates how coupling-mediated, access-closure, and shaft-mount patterns yield an explainable partial ordering suitable for precedence compilation. The resulting framework complements CAD/STEP with explicit, auditable connection semantics for precedence generation.