Against (current) test 48 (document's language)

Hi,

I don't agree with the current (as written) test 48 at 
http://www.w3.org/WAI/GL/WCAG20/tests/test48.html (Content has required 
lang attribute(s).).

The test does not consider that XHTML Basic 1.0 documents can't use lang 
attributes (only xml:lang attributes are allowed).

As a result, the test at
http://checker.atrc.utoronto.ca/servlet/resolve?file=http%3A%2F%2Fwww.it.uc3m.es%2Fvlc%2Findex.html&group=3.1+meaning&type=known&guide=wcag-2-0-aa.xml&lang=eng
returns a false barrier (xml:lang is enough).

Comments?

Vicente Luque Centeno
Dep. Ingeniería Telemática
Universidad Carlos III de Madrid
http://www.it.uc3m.es/vlc