HTML Tidy accessibility-check 1.0/5.2.1

This file demonstrates a <table> that may require markup (column headers)

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
<title>alert 1.0/5.2.1</title>
</head>
<body>

<table width="80%" border="1" summary="This data table should use markup to associate multiple levels of row and column headers">
    <caption>This data table should use markup to associate multiple levels of row and column headers</caption>

    <tr>
        <th>ID</th>
        <th colspan="2">System<br/>Color or Name</th>
        <th>Required</th>
    </tr>

    <tr><td>a-1</td><td>blue  </td><td>      </td><td>yes</td></tr>
    <tr><td>a-2</td><td>      </td><td>Susan </td><td>yes</td></tr>
    <tr><td>a-3</td><td>green </td><td>      </td><td>no </td></tr>
    <tr><td>a-4</td><td>orange</td><td>      </td><td>no </td></tr>
    <tr><td>a-5</td><td>      </td><td>Frank </td><td>yes</td></tr>
    <tr><td>a-6</td><td>      </td><td>Harold</td><td>no </td></tr>

</table>

</body>
</html>