Code hopping means that when the card is swiped at the POS machine, the merchant code on the consumption bill does not correspond. Generally, after using a POS machine to swipe a card, each credit card swipe purchase receipt will have a merchant code consisting of 15 digits. Generally, the first three digits are the code of the acquiring bank, and the fourth to seventh digits are the administrative division codes, representing the location of the merchant. Region, the eighth to eleventh digits are the merchant code (MCC code). Code hopping means that the MCC code in the UnionPay system is different from the MCC code on the credit card consumption receipt. For example, the transaction receipt clearly says 7011 Hotel, but the query in the UnionPay system is 5411 Supermarket. This is a typical code hopping.