Dragos documents OT asset visibility, vulnerability management, threat detection, and response capabilities. An observed inventory and communication map can inform architecture review, but it cannot decide the approved security zones, conduits, trust boundaries, safety constraints, or change plan for a live industrial system.
NIST SP 1800-45 documents three secure remote-access reference designs demonstrated with commercial technologies in a lab. The guide can sharpen architecture and acceptance questions, but it does not authorize a connection to a live water or wastewater control environment.
Waterfall documents a hardware-enforced one-way transfer architecture with software that replicates OT data for external use. That boundary can serve a defined conduit, but it does not design every zone, identity, remote-access path, exception, monitoring control, or recovery decision.