It means that if you do inter-period arbitrage, if the price difference is still unfavorable to you when the delivery month of the near contract is near, and you are a legal person customer and can deliver, then you can buy the warehouse receipt of the near contract and then transfer it to the far month, that is, sell it for delivery in the far month. Through two deliveries, lock in the fixed profit when the spread is greater than the cost at the beginning of arbitrage. It can also be said to be risk-free profit.

Or you say that the warehouse receipt is not a delivery match, but the customer reaches an agreement privately to trade the warehouse receipt (transfer), or transfers the warehouse receipt to other customers by cash installment.