I see there are a number of extra js files I was not aware of that rare eferred to in the source code of pages generated by DNN on one of my sites. The following are the javascript files are referecned in the HTML:

dnn.xml.js
dnn.xml.jsparser.js
dnn.xmlhttp.js
dnn.xmlhttp.jsxmlhttprequest.js

I did some checks across a number of different DNN sites and many have these files in the source of a DNN generated HTML page, but equally there are many DNN sites whose pages do not have any reference to these js files and some that make reference to some, but not all, of theses files (e.g. dotnetnuke.com).

Can anyone advise:

a) what these js files do?
b) why they do not appear in the HTML of all DNN sites? (is it only some versions of DNN that gnereate these references? Or is maybe related to a skin or a menu provider or a host setting or soemthing else?)

Thanks!