EDIT: What is American Theft Protection?
Good question! They never told me anything about that either.
my guess would be it's one or both of these products from the "theft protection" tab at the link i gave earlier:
ATP® Window Etch System
The ATP ® (Automotive Theft Protection) Window Etch System has proven to be one of the most effective theft deterrent products available. A unique identifier is permanently etched into the exterior glass on several windows of the vehicle, which deters theft and, if the vehicle is stolen, makes recovery easier. ATP Window Etch cannot be removed and will not wear off.
ShadowMark® Vehicle Body Labeling System
ShadowMark ® is a highly effective theft deterrent that is also easy to apply. Technicians mark a unique identifier on hidden areas of the vehicle body. When a UV light shines on the area, the identifier will fluoresce, allowing law enforcement officers or recovery teams to quickly, easily identify the vehicle.