First timer on the DDP - how do you know if an item is valid as a snack credit. Do you ask at check out or is it clearly marked? Do you have to let the attendant know you want to use a snack credit when you go to purchase? Can some items go towards snack credits and others not? Sorry if i sound confused i just want some advice on the best way to use the credits (to be clear I'm not asking for ways to get the best value for my snack credits merely how they actually work at the point of purchase). Cheers.