Basically it is a "body data tag". I believe what that means it relates to the body of the car before it goes to the paint process. Any hole that needs to be drilled or punched are processed before the paint is applied. So moldings or brackets for specific options that need to be added to the body are applied before paint, ie vinyl roof, power brakes, A/C, outside mirror, side or hood scoops etc, etc. Prevents corrosion and possible damage to the final finish. Just my thoughts and opinion. Others may know more.