Status: IN
Visitor's double-dispatch protocol (Accept delegates to a type-specific Visit method) is precisely the mechanism that implements OCP axis inversion: the two-class-hierarchy structure makes the tradeoff of type extensibility for operation extensibility explicit and structural rather than implicit.
The dispatch mechanism IS the axis inversion — not two independent properties but implementation and consequence
Depends on (SL): visitor-double-dispatch-mechanism, visitor-inverts-ocp-axis