What classifieds a restaurant to be a fast food Restaurant?

This is hopefully a simple question that can get answered. I'm asking this due to the fact that i recently when to a place that classified themselves as NOT being a fast food restaurant.What classifieds a restaurant to be a fast food Restaurant?
Fast food Restaurant (also known as Quick Service Restaurant or QSR within the industry itself) is the term given to food that can be prepared and served very quickly. While any meal with low preparation time can be considered to be fast food, typically the term refers to food sold in a restaurant or store with preheated or precooked ingredients, and served to the customer in a packaged form for take-out/take-away. Regular restaurants start making the food when it is ordered and is not precooked. This makes service longer lasting between 20-45 minutes.
FASTWhat classifieds a restaurant to be a fast food Restaurant?
Well if the restaurant sells fried/greasy food, and its obvious that the food isn't fresh then the restaurant would be classified as a fast food restaurant.What classifieds a restaurant to be a fast food Restaurant?
I believe a meal that SHOULD take less than four minutes to serve.