Access: [1.1.1.12]: <img> missing 'alt' text (horizontal rule)
(Priority 1)

Cause:

All images require text equivalents including those used to indicate breaks within a web page. If an image is used as a horizontal rule, it should include the following "alt" text: alt="*" or alt="horizontal rule".

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>aert1.0/1.1.1</title>
</head>
<body>
<img src="bar.gif" width="200" height="5"/>
</body>
</html>

References:

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