The compliance rules are explicit: back-to-back LCs and offshore resale are structures banks watch closely. Bank of China does not want a stack of scans; it wants goods flow, fund flow and document flow to agree. Our method runs the three sets of papers through one rules model.

The bill of lading carries load port, vessel and B/L date; third-party inspection carries volume, quality and sampling time; the payment flow carries counterparty, amount, currency and date. The model first checks whether “B/L date plus voyage” can cover the “inspection sampling time,” then whether “flow amount times FX” lines up with “B/L volume times contract price.” Any mismatch turns red for manual review before the bank ever asks.

The point is not sophistication but making “genuine trade background” a machine-readable evidence chain. Run the model clean before opening a new credit, and Bank of China's settlement desk sees a consistent chain instead of a folder needing explanation. This also ties to the sanctions line: Iran-origin is an automatic reject, enforced as a one-vote veto on the origin field in the model.