handling of POST in XMLHTTPRequest.

Hi All,
We have recently run into a case where XMLHTTPRequest is being used to
POST content, but the javascript author has failed to add the mandatory
content-type header. We were wondering what the default content type
should be. We believe that it should be the same default as the default
content type for a FORM post.
Oddly enough, the w3 draft spec for xmlhttprequest does not even state
that you should provide a content-type when posting:
http://www.w3.org/TR/XMLHttpRequest/#dfn-send
whereas XULPlanet at least states one should be provided:
http://www.xulplanet.com/references/objref/XMLHttpRequest.html#method_se
nd
"The MIME type of the stream should be specified by setting the Content-
Type header via the setRequestHeader method before calling send."
neither say what the default should be.

Thanks
David Carson
Nokia S60 Browser