Ecco un esempio:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Tabella</title>
<style type="text/css">
<!--
.centro {margin-left:auto;
margin-right:auto;}
body {text-align:center;}
//-->
</style>
<script type="text/javascript">
<!--
function replace() {
document.getElementById("studente").innerHTML="Ciccio Cappuccio";
}
function reset() {
document.getElementById("studente").innerHTML="-";
}
//-->
</script>
</head>
<body>
<div>
<table border="1" class="centro">
<thead>
<tr>
<th>Ciccio Cappuccio</th>
</tr>
</thead>
<tbody>
<tr>
<td id="studente" onmouseover="replace()" onmouseout="reset()">-</td>
</tr>
</tbody>
</table>
</div>
</body>
</html>
