If done order
The If-done order is a kind of orders regarding to combination. It is made by two steps of limit orders or stop loss orders. The first one is filled, the other would work well. In other words, the second order does not go valid unless the first one is executed. You need to pay attention that the If-done order is quite different from the OCO order.
How to use the If done order
If you have intention to make a new position using a single order, you might miss the chance to take profit during you are asleep. Two single orders without any position might make you in trouble in case that the order to take profit might be filled in advance to the orders to make position. If-done order is useful and safe because the order to take profit keeps invalid until the fresh position is built up.