[1] XML in HTML Meeting Report, 2017-10-02T11:00:11.000Z, 2024-08-17T05:15:52.300Z https://www.w3.org/TR/NOTE-xh#sol
XHTML, text/html
[25] Re: Sniffing XHTML sent as text/html from Steven Pemberton on 2000-09-13 (www-html@w3.org from September 2000) http://lists.w3.org/Archives/Public/www-html/2000Sep/0024.html
MIME Sniffing, DOCTYPE switch