Discount is an industry term. For CIF trade, discount usually means freight+management fee+profit. For FOB trade, the freight and management fees incurred during transportation are not included. General traders will give their customers a discount on when and where to deliver goods. CP+ discount is the actual cost price. Because CP is only a listed reference price, and the spot price is often higher than CP according to the abundance and shortage of goods, in order to reflect the constant CP in CP+ discount, the discount price often fluctuates, and sometimes there will be zero discount or negative discount when the goods are sufficient. The fluctuation of quality will have a certain impact on the discount, but it mainly depends on the freight and CP price mentioned above.