Position opening refers to a situation in which an investor newly buys or sells a certain quantity of stock index futures contracts. If the investor keeps the contracts till the last trading day, he/she will have to conclude the deal by way of cash settlement.
Position closing refers to a situation in which an investor concludes a deal of stock index futures by buying or selling in opposite direction the stock index futures contracts which have the same variety, quantity and delivery month with that held by he/she before.
The contract which has not been concluded by the investor after position opening is called open contract. After position opening, there are two ways for investors to conclude stock index futures contracts, either closing position at a proper time or keeping it until the last trading day for cash settlement.