The chicken egg paradox of using help files

Does anyone know of the existence and whereabouts of a definitive reference AS2 to AS3 dictionary of where I can look up a method, function, class, etc and get to see the AS3.0 equivalent.

This would make using and learning AS3.0 so much easier and accessible, because as so often is the paradox of using “help”, you need to already know the terminology of what you are looking for before you start.