Buy flat today: refers to selling multiple orders bought on the same day when placing an order.

Selling flat today: refers to selling empty orders bought on the same day when placing an order.

Close position: that is, no matter how many empty orders are thrown.

"The closing order of Shanghai Stock Exchange is to place an order with Pingjin Warehouse"

In other words, "the closing orders of the Shanghai Stock Exchange all mean that buying on the same day must be sold on the same day or selling on the same day must be bought on the same day". In other words, the futures spot market often says "no floating orders", which means orders that are not overnight, that is, orders that must be settled on the same day.