HTML Tidy accessibility-check 1.0/5.2.1

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<title>alert 1.0/5.2.1</title>
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<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>

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    <tr><th            >System                   </th><td>a-1  </td><td>Susan     </td><td>Macintosh </td></tr>
    <tr><th rowspan="2">ID location<br /> or code</th><td>Local</td><td>Building 1</td><td>Front Desk</td></tr>
    <tr>                                              <td>Local</td><td>Building 2</td><td>Back Desk </td></tr>
    <tr><th            >Required                 </th><td>yes  </td><td>yes       </td><td>no        </td></tr>
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