Currently we calculate position based on the unit size & nominal value of the positions.

For example, if I buy 10 units of NQ at 15,000, then the nominal value would be $150,000 (the total value of the position) and the position size with be 10. These are not 10 contracts. So you can take partial profits and take only portions of a unit, whereas with contracts you cannot.

Imagine a unit is like an apple. You want to buy 2 apples (unit size) at $10/apple, so you spend $20 (nominal value). You then sell the apple at $12/apple, so the nominal value of the position is $24. You sell the 2 apples for a profit of $4 ($24-$20 = $4 profit)

We want to make the trading environment as real as possible, so we will be looking to make our futures trading in contracts.