XML header and childNodes

I discovered something really odd today that maybe a seasoned AJAX guru already knew as a legendary bug which might even have a name. I was developing a little AJAX method on the server side that returned this:

<?xml version="1.0"?>
<sections>
  <section>
    <number>001</number>
    <title>PLug 1</title>
  </section>
  <section>
    <number>003</number>
    <title>PLug 3 xyz</title>
  </section>
</sections>

Note: The Content-Type used was "text/xml"

I used jQuery to kick off the AJAX call and then I loop over the document element returned with childNodes almost like this:

children = data.childNodes[0].childNodes;
for (var i=0, len=children.length; i<len; i++)
  // bla bla

It was working fine in Firefox and of course not in IE 6.0.

Long story short, the solution was to not attach the first line: <?xml version="1.0"?> because with that line, in IE the object data.childNodes[0].childNodes did not contain any further nodes to loop over. Why??? No idea. So now my server side sends this instead:

<sections>
  <section>
    <number>001</number>
    <title>PLug 1</title>
  </section>
  <section>
    <number>003</number>
    <title>PLug 3 xyz</title>
  </section>
</sections>

To make it work now I just removed that first line. I haven't had to worry about unicode problems yet but I would use this first line to describe the unicode encoding if non-ASCII. Now I can't, which makes me a bit worried that I might run into encoding problems one day.