NIST's operational technology guidance treats performance, reliability and safety as requirements that need attention alongside security. GFT applies that principle by separating the safe physical response from the survival of information. A powered gateway has no authority to defeat a protective stop, and a production restart needs its own approval conditions.[S03]
Consider an illustrative cutting-to-sewing bundle. Its identifier is assigned before transfer, and a supervisor records its release from cutting on a locally powered terminal. Mains supply then fails before sewing begins. Assume that the approved machine response brings the process to a safe stop while the terminal, its local network path and the record store remain powered. These are explicit scenario assumptions, not descriptions of an installed GFT factory.
In that illustrative situation, the accepted cutting-release event can remain available even though the next production operation has not occurred. The supervisor can locate the bundle, distinguish waiting material from completed sewing and identify the event still awaiting remote acceptance. A management screen may continue to show an older count until communication returns. The screen's age and the bundle's state answer different questions; neither should silently substitute for the other.
GFT proposes that inspection availability be stated separately. If a camera, illumination unit or associated computer is outside the protected circuit, assume its inspection result is unavailable during that failure unless another qualified method exists. A surviving record store cannot create a measurement that the inspection system never made. An operator should see whether a missing result means not inspected, inspection failed, communication pending or inspection held for review.
The proposed state table in Exhibit 2 makes these distinctions explicit. It assumes that local safety functions are independently approved and that a protected record terminal remains available during mains loss. A LAN failure means the ordinary terminal-to-store path is unavailable; the suggested local-entry alternative applies only where a separately qualified terminal store exists. The dispositions are illustrative requirements to discuss with the operator, not permission to run a process.
A useful illustrative contrast is a gateway that stays alive while its input sensors go dark. Its health message may still arrive, but that proves only that the gateway could send that message. GFT recommends recording the affected source set and the beginning of the observation gap. Do not convert absent machine pulses into a claim that the machine produced nothing. The operator may be unable to distinguish stopped production from lost observation until local checks resolve the uncertainty.
The reverse distinction also matters in the proposed design. Some work might remain physically possible while the authorised recording route is unavailable. The correct response could be a controlled manual procedure or a production hold, depending on the consequence of losing traceability. Define that choice before an outage. Otherwise the shop floor must invent a policy while trying to restore service, and different shifts may attach different meanings to apparently comparable counts.
GFT recommends defining the meaning of a hold at the work location. Identify the affected material, the reason for withholding release and the role that can clear it. A hold should remain visible when reporting is delayed. Its cancellation should refer to the evidence that resolved the condition. This makes the proposed record useful to the person moving the bundle, rather than only to the person reviewing totals after the shift.
For the illustrative bundle journey, recovery begins with physical identification and the retained event, not with the colour of a network icon. The supervisor checks that cutting release was accepted, sewing remains pending and any manually observed movement has a documented status. Only then should the reporting system incorporate the reconciled events. The lesson is a boundary rule: an application restart, an inspection restart and permission to resume production must each have an explicit meaning.