I've wrapped that fragment in a test page (http://www.chiark.greenend.org.uk/~janetmck/amirightornot.html) and you're right, it doesn't validate (http://validator.w3.org/check?uri=http%3A%2F%2Fwww.chiark.greenend.org.uk%2F%7Ejanetmck%2Famirightornot.html&charset=%28detect+automatically%29&doctype=Inline).

Now, how do I go about telling software developers who are senior to me (and who know I'm not in a "technical" role) that they're wrong?