Article 14 of SAFE's Guidelines on Foreign Exchange Business for Trade in Goods pins down the settlement structure for offshore transshipment: in principle the same deal must be handled at one bank and in one currency. Cross-bank or cross-currency execution requires confirmation of authenticity and legality, and the cover note for the external payment declaration must read "special offshore transshipment," reported to SAFE within five working days of the transaction.

This is a hard constraint for crude-oil arbitrage. Back-to-back letters of credit and title transfers all run under these rules, and the room for currency mismatch is narrowed sharply. In practice the safe path is to commit to one bank and one currency, running the whole settlement through a single channel, and to treat "special offshore transshipment" as the exception rather than the norm.

Direct CIPS clearing compresses the settlement cycle from T+2 to T+1, and together with the single-currency rule it lowers the operational friction on the banking side for transshipment desks. The precondition is clean documents and reconciled records, with a verifiable title-transfer timestamp — exactly the gap that on-chain SHA-256 can fill.