throws URIReferenceException {
        String uri = uriReference.getURI();
        if (uri.equals("http://www.w3.org/TR/xml-stylesheet")) {
            try {
                FileInputStream fis = new FileInputStream(f);
                return new OctetStreamData(
                    fis, uriReference.getURI(), uriReference.getType());
            } catch (Exception e) { throw new URIReferenceException(e); }
        }
        // fallback on builtin deref