Shanghai Futures Exchange

The seller's customers are open to the seller's members, and the seller's members are open to the exchange, and then the exchange is open to the buyer's members, and the buyer's members are open to the buyer's customers (except gold).

Dalian Commodity Exchange and Zhengzhou Commodity Exchange

The seller's customer directly issues the invoice to the buyer's customer, and the exchange will verify it (after the seller issues the invoice, the exchange will pay the remaining 20% of the payment to the seller). ...