The term stock index futures refers to the fact that all contracts in the last month (not the current month, explained below) are continuous, because their prices change differently in different contract months. For example, the price in the delivery month is closest to the spot price, and the contract transactions after three or four months from the delivery month are the most.

Next month continuously:

Continuity of next month (IFL 1): refers to the continuity of all recent contracts in next month.

The next season is continuous:

The price of the next quarter after the main contract (referred to as the first quarter);

Every other season:

The price in the second quarter after the main contract (plus 3 months on the basis of the next quarter);