The printed piece of plastic(I assume) with the labels for all the knobs and buttons on it. I don't know what any of them do for sure, but I can guess on most. It'd help to have my car in the body of my post: '84 300D Turbo Diesel.

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1984 300D Turbo Diesel - 211700+ mileage (now sold)
http://www.maj.com/gallery/Ned/benz/sig.jpg
In any of my posts, it is safe to assume
that I'm talking about this car.