'rules' controls which portions of a table's borders are displayed
<HTML> <body> <table id="myTable" border="3" rules=""> <thead> <tr> <td>Header</td> <td>Header</td> <td>Header</td> <td>Header</td> <td>Header</td> <td>Header</td> </tr> </thead> <tr> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> </tr> <tr> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> </tr> <tr> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> </tr> <tr> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> <td>Cell</td> </tr> <tfoot> <tr> <td>Footer</td> <td>Footer</td> <td>Footer</td> <td>Footer</td> <td>Footer</td> <td>Footer</td> </tr> </tfoot> </table> <br> <button onclick="myTable.rules='none'">none</button> <button onclick="myTable.rules='all'">all</button> <button onclick="myTable.rules='cols'">cols</button> <button onclick="myTable.rules='groups'">groups</button> <button onclick="myTable.rules='rows'">rows</button></body> </HTML>