Every transition changes assurance
The boundary may cross owners, credentials, networks, protocols, time domains, data semantics, model assumptions, or physical authority. Record what evidence is required on each side.
Inside the twin
State, data, models, simulation, AI and analytics, APIs, and decision logic have separate identities, versions, privileges, and failure modes. “The twin” is rarely one component.
Design questions
- Which source is authoritative, and for how long?
- How are identity, provenance, freshness, units, and quality verified?
- Who may modify models or decision policy?
- What independently limits physical commands?
- How does the system expose uncertainty and recover synchronization?