Another Code to reproduce the Bug:
----------------------------------
$dom = new DOMDocument('1.0', 'ISO-8859-1');
$dom->load('file.xml');
$iterator = new RecursiveIteratorIterator($dom->childNodes, RecursiveIteratorIterator::SELF_FIRST);
 
foreach($iterator as $name => $element) {
  print $name . "\n";
}

Expected result:
----------------
A recursive List of all Elements

Actual result:
--------------
"Catchable fatal error:  Argument 1 passed to RecursiveIteratorIterator::__construct() must implement interface Traversable, instance of DOMNodeList given, called in [?] and defined in [?]"

This bug exists further reproducibly on PHP5.2

Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

DomNodeListe implements Traversable. You can convert a Traversable object to an 
Iterator using the IteratorIterator 
class.

<?php
$xml = '<queries><query attr1="value"></query></queries>';

$doc = new DOMDocument;
$doc->loadXML($xml);

$queries = $doc->getElementsByTagName('queries');
$nodes   = iterator_to_array(new IteratorIterator($queries));
?>

iterator_to_array() accepts any terversable, therefore there is no need to wrap 
the DOMNodeList into an IteratorIterator first, it can be converted to array 
*directly*

<?php
$xml = '<queries><query attr1="value"></query></queries>';

$doc = new DOMDocument;
$doc->loadXML($xml);

$queries = $doc->getElementsByTagName('queries');
$nodes   = iterator_to_array($queries);
?>

The key used per each node is some kind of ID (positive, long integer) and it 
seems to be unique. Using an array can be useful because a DOMNodeList 
automatically re-orders if nodes therein are deleted. This is not the case with 
the array (naturally).