In the court of King Louis IV of France, when you were invited to a dinner party or feast, there were some interesting etiquette rules to be followed:
At the door of the dinner room, you did not knock, but you "scratched" on the door with your Left Fingers only,
After being led to your seats, to sit you approached the seat from the Left side. If you had to excuse yourself from the table, you exited your seat from the Right side,
He also introduced table napkins so you did not have to wipe your face with the table cloth. Personally, I always thought the table cloth was much softer.