1. futures index: refers to futures contracts with index-based assets, such as stock index futures. The commodity index calculated by weighting the trading volume of each contract is generally recorded as an index in commodities, while it is directly recorded as a weighted contract in CICC, such as IF weighting.

2. Futures main force: the continuity of the main contract, that is to say, the main contract is the mechanical connection of all the main contracts, forming a continuous contract, and the daily trading volume and positions are the largest, which will form a relatively continuous K-line chart. Which is the main contract.

So these two methods can't be bought directly, only futures contracts can be bought.