>here i have XML:
No you don't. You have something that would be XML if you put a wrapper element around it. Without that wrapper element, it's not an XML document.
One way to add the wrapper element is to reference your file as an external entity from a skeleton document that adds the wrapper, like this:
<!ENTITY e SYSTEM "original.xml">
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference