Access: [3.6.1.2]: list usage invalid <ol>
(Priority 2)

Cause:

Avoid using list markup to create formatting effects. Do not use 'ol' (ordered list) to indent text, use Cascading Style Sheets (CSS) instead.

Testfile:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
	"http://www.w3.org/TR/REC-html40/loose.dtd">
<html lang="en">
<head>
<title>aert1.0/3.6.1</title>
</head>
<body>
<ol>
 This is only for the indent.<br/>
 And this as well.
 <ol>
 A further indent.
 </ol>
</ol>
</body>
</html>

References:

W3C WAI: http://www.w3.org/WAI//
HTML Techniques for WAI 1.0: http://www.w3.org/TR/WCAG10-HTML-TECHS/