>>>>> "Vyacheslav" == Vyacheslav Sedov <vyacheslav.sedov@xxxxxxxxx> writes:

    Vyacheslav> most pages in WWW not well-formed XML? Tidy can help -
    Vyacheslav> is here possibility to implement tidy as buillt-in
    Vyacheslav> function to XSLT?

Yes. But it isn't necessary. 
It's neater to have the implementation of doc()/document() invoke
tidy. Either directly, or indirectly via a URI resolver.
-- 
Colin Adams
Preston Lancashire