And that is why so many developers prefer to work in flash or silverlight. HTML will never be a standard as long as major browsers only support parts of it. Those development languages include the validation in the complier.
It is only asking for misuse of a schema to release a 'standard' with little documentaion and no validation. Arrh, the good ond days of IE6 and every second line of HTML being a test for what the browser is.