When futures are delivered, because the spot prices are different in different places, some positions will be set as standard libraries, and the futures price is the price at the time of delivery in these warehouses. Other warehouses will give this standard warehouse a certain discount.

For example, the price of rebar is 3000 in Hubei, 2800 in Hebei and 3500 in Guangzhou. If the warehouse in Hubei is set as a standard warehouse, 300 yuan will only need 2800 yuan to get the goods in Hebei, which means there is a discount from 200 yuan.