xml in netscape

Hi, i am working on dynamic select lists. i don't want to show my xml code in source. it work in ie good but not in netscape and mozilla. they want an xml file but i don't have a xml file i generate my xml code dynamically. i use javascript dom. i know ie use ActiveXObject but i tried netscape xml object generating code i mean document.implemantion... i have not been succes yet. When i print my xml code in php with echo function ie shows it but netscape or mozilla does not show it like ie. i use xml object load method like this:

xmldoc.load("xmldoc.php");
and i write the xml code on screen in xmldoc.php with echo

how can i do it?
thanks