Correct etiquette including the formal authority Emily Post (both Pre-World War 2 , and Post War 2 books/manuals, stated that hats should be worn in common areas of a building and supposed to be kept on in commercial establishments. Also at Cafes, Bars, and Saloons a hat is appropriate to wear inside. One may Also wear a hat inside if he is seated at the bar section of a restaurant. If he is to be seated at a table the gentleman has the option to take it off when he enters the restaurant or at his table right before he sits down(Or right before he waits for his company to be seated).
