Access: [5.5.1.3]: <table> summary invalid (spaces)
(Priority 3)

Cause:

Table summaries must contain an actual value (i.e. summary=" " with spaces is not acceptable). The summary should describe the relationship among table cells and cells that span multiple columns and/or rows. It is also useful in describing how the information contained in the table relates to other information in the document.

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>aert1.0/5.5.1</title>
</head>
<body>
<table summary=" ">
	<caption>This table has an invalid summary (all spaces)</caption>

	<tr><td>1</td><td>2</td></tr>
	<tr><td>3</td><td>4</td></tr>

</table>
</body>
</html>

References:

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