Yes.
> according to
> [31] extSubset ::= ( markupdecl | conditionalSect | PEReference
> | S )
>
> there is no requirement that the external subset begin with a document
> type declaration.
It is a requirement that the external subset *not* begin with a document
type declaration.
> which would mean that the only indication of the root element type comes
> from the refering declaration. which would mean that distinct xml
> documents could well specify different root elements with respect to the
> same external subset.
>
> is this intentional?
Yes.
James