Erm, where you looking for yet another XML class? In that case there are two of them in AS3. But, of course, you can write more of those if you want. Or did you mean that how Flex framework manages components? If so, it hardly is a DOM, well, it's way more complex than that. Document Object Model is a very wide definition which is above framework or even language concepts. On the other hand it may be implemented using almost any programming language. So, essentially, what you asked sounds more like "do computers have squares?" - well, one can answer, sure they do, but this won't be a helping answer, because it's obvious that the question was meant to ask something different.
Best. Oleg