T+D means T-day trading, and related reverse operations can only be carried out after D-day. T+0 means trading on the same day (futures are generally trading on the same day). T+ 1 means to sell one day after buying (that's how stocks in China are traded). Buying a position means that there is no position at present, you have bought a new bullish futures contract, and you are buying and closing your position until the delivery date. . .