PHP应用XML的问题急急急！！！！！！！！

post.php

<?php
$doc = new DOMDocument('1.0','gb2312');
$doc->formatOutput = true;
$root = $doc->createElement($_POST['N']);
$root = $doc->appendChild($root);
$title = $doc->createElement($_POST['T']);
$title = $root->appendChild($title);
$text = $doc->createTextNode($_POST['E']);
$text = $title->appendChild($text);
echo 'Wrote: ' . $doc->save("test.xml") . ' bytes';
?>

----------------------------------------------------------------------
index.html

<form action="post.php" method="POST">
<input type="text" name="N"><br />
<input type="text" name="T"><br />
<input type="text" name="E"><br />
    <input type="submit" name="submit" value="Submit me!" />
</form>
我要批量提交数据应该怎么写.