Good question, I'm not sure. So you're saying that `dyn.b*` isn't necessarily a dynamically generated UTI?
I'd probably disagree. I think (with no grounds) that Apple uses `dyn.` to mean dynamic, and `a` means 'of type a'. Maybe `dyn.b*` will mean version 2 of the dynamic UTI type (e.g. with a 64 bit encoding with a different encoding vector - whatever they are :S)