Re: document() can not used in IE6?

The document() function may be supported in IE, but only if your security
zone is local and not the Internet.  IE for security reasons may be
disabling the document() function if you are browsing a page on the
Internet and the page tries to do a client side XSL transform.  The
document() function however, is supported in the underlying MSXML DLL.

With the document() function you can fetch any XML document, _provided_
it comes from the _same_ domain (same in Fx and IE). I think Firefox is the
only browser with a built-in support for such cross-domain fetches - built-in
here means you can authorize those domains manually (maybe this feature
will be dropped soon).
If you want to use a web-service (from Google or Yahoo or any) which
delivers XML and you want to process this XML clientside (in the browser),
then you have to receive it via a proxy web-page from your domain to avoid
cross-domain.