The number of purchases is the number of active purchases.

Sales volume is the volume of active sales.

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Volume: refers to the number of commodity futures contracts bought or sold in a certain period of time, usually the number of contracts traded in a trading day.

Closing position refers to the amount of closing position;

Open position refers to the volume of open position (that is, whether it is buying or selling, as long as it is the sum of new orders entering the market);

Volume refers to the total volume of sales contracts;

Open position refers to the total amount of open contracts.

The position difference is the sum of all open contracts.