There are two kinds of rolling deposits, one is the number of barrels, and the other is the rolling deposit of funds. The number of barrels transferred is how many barrels or barrels you buy in the next period, but the price is much higher than the cost of your last period. Rollover of funds means that the funds before you roll over are transferred to the next trading period, but the funds are unchanged, and the number of barrels you hold in the previous period will decrease accordingly. It is equivalent to selling and buying, but it may be much higher than the new opening price ratio.