Short position means that the original short position is bought and closed, and the new short position is sold and opened, and the position remains unchanged.

Short position is a futures term, which means that short positions change hands. The standard name of air combat is "air combat"

The so-called change of hands means the transfer of orders (futures contracts) in the same direction, which are divided into multiple delivery and empty delivery according to their nature. Empty orders change hands: if the original selling orders in hand are to be closed, they must be repurchased. Someone else must have sold it at this time. If he opened a position, the position in the market did not change at this time, but the sell order was changed from my hand to his hand. This is called empty exchange.