XHTML col must be included in <colgroup> and no specific end tag is needed.
<colgroup>
<col class="label" />
<col class="value" />
</colgroup>
The following validates to XHTML Strict !
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html lang="sv">
<head>
<title> Strict DTD XHTML Example </title>
<link rel="stylesheet" type="text/css" href="theme.css" />
</head>
<body>
<p>paragraph</p>
</body>
</html>