Dr. Octo Rex patches can consist of up to eight separate REX loops. When you load an Dr. Octo Rex patch, the REX loop(s) will be automatically loaded in the Loop Slots with their names shown in the display(s) below each button.
Songs created in earlier versions of Reason that used Dr. Rex devices will open just fine in this version of Reason. Any Dr. Rex devices will be replaced by Dr. Octo Rex devices and the corresponding REX loop will load in Loop Slot 1. The original Dr. Rex device settings will be translated as follows: