If you test it in W3C's Validation Service:
https://validator.w3.org/#validate_by_input
And give it XHTML with a "</p>>":
Code:
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
</head>
<body>
<p>Test</p>
<p>And here's an error.</p>>
</body>
</html>
you get a "character data is not allowed here" error.
If you feed it similar in HTML:
Code:
<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<body>
<p>Test</p>
<p>And here's an error.</p>>
</body>
no such error. It thinks it's fine...
If you do "<<p>" instead, both the XHTML1.1 + HTML5 checkers ping it.
Must be something obscure/weird in the HTML spec. Reminds me when I found that bug with the accidental <p">, and KevinH tracked it down. Turns out such a thing IS valid in HTML... but
extremely poor practice.