role should be a list of QNames

Hi,

The role attribute is now just a QName, but should be a list.
- just like the class attribute
- needed when using multiple microformats
- needed when different user agents define different GUI role QNames

(This got no responses on www-html so it seems nobody has a problem with 
this)

-- 
Sjoerd Visscher
http://w3future.com/weblog/