What is, and is not meant, by size when it comes to the subatomic world? The FAQ's of this forum, and a wikipedia article I read recently seem to agree that "the very notion of a discrete 'particle' has been ultimately replaced by the concept of something like wave-packet of an uncertain boundary". I think I like that statement, but I still read from time to time that subatomic particle P has size less than 10^-M meters, for example. How would one conclude that without assuming a certain boundary? In what ways do these size statements have meaning and in what ways do they not have meaning subatomically?