What is the Wrinkle Guard feature and how does it work?

Wrinkle Guard helps keep permanent press items wrinkle-free if you don't unload the dryer promptly at the end of an automatic cycle. If the door is not opened, it will tumble clothes without heat periodically — for about 30 minutes on Wrinkle Guard I, 40 minutes on Wrinkle Guard II, and approximately 2.5 hours on Wrinkle Guard III. (Page 35)