This command is only available if you have selected an Entry order. It allows you to bind this Entry order into an OCO pair with another, existing Entry order.
The dialog box will appear:
If there are existing OCO linkable orders, they will be listed in the drop-down box.
If the original order is already part of an OCO pair, the dialog box will contain a warning:
Remember, there are limitations on the types of orders that can be part of an OCO pair.