Explain the reason:

Now let's explain the principle of zero slip point. For example, reverse documentary, the current buying price is 1000, and the selling price is 100 1. At this time, when the trader pays the bill, the original transaction price will be 100 1, but in mirror documentary, the trader only submits the transaction. The firm offer is immediately sold at the market price, and the final transaction price is 1000, and then the price of 1000 is returned to the trader, and the trader finally closes the order for 1000.