so does the vessel have to be a closed system in order for it to have ullage? ullage seems from these excerpts (and BTW, thanks Dr. Bill!) to have a great deal more to do with quantifiable pressure and such than simple volume of space unoccupied by liquid, as i had imagined it to be this morning when i first heard the word.

would it, then, be incorrect usage to say that the quality of a restaurant is generally directly proportional to the ullage allowed by the waiter who is pouring your cabernet?