<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>table dom test</title>
<style type="text/css">
  table {width:200px}
table[summary="summ"] {font-size:24pt}
</style>
<script type="text/javascript">
function dom(){
var t = document.getElementById('t2');
t.summary="summ";
}
</script>
</head>

<body onload="dom()">

Both tables should look identical

<table id="t2" border><caption>caption</caption><tbody><tr><td>cell1</td></tr></tbody></table>

<table id="t2" summary="summ" border><caption>caption</caption><tbody><tr><td>cell1</td></tr></tbody></table>

</body>

</html>