> > Me too. Turing completeness is not the same as closure over 
> the data model.
> > To take an obvious example, there is no way of creating a 
> result tree that
> > contains an unparsed entity, even though the data model 
> allows unparsed
> > entities to exist.
> 
> Closure only implies that you never create anything not in 
> the set; not 
> that you can create everything in the set.

Thanks for the correction, you're right of course. Is there a term for what
I was trying to express: "complete coverage", perhaps?

Michael Kay