For different contract months of the same commodity futures, the spread is generally calculated by subtracting the far contract from the near contract; For futures contracts of different commodities in the same industrial chain or directly across commodities, the futures price difference between them is generally calculated on the basis of contracts in the same month. Generally, the high price is deducted from the low price. In the case of cross-commodity, sometimes the price of one commodity and another commodity is high or low, and then it is generally indicated who has deducted the price.