Question in dhtmlxform.send()

I’m using dhtmlxform.send(url,mode,function(xml){…}).
The manual doesn’t say more about para “xml”.
I think xml should be the response from “url” to indicate the information about processing in url.
But when I use this function, xml isn’t the response(url generates a xml output) from url, but an object.
I use the scripts in function(xml){…} as follows to show what it is:
for(var i in xml)alert(xml[i]);
It turns out that xml is an dtmlXMLLoaderObject in dhtmlxcommon.js.
Can anyone explain it ?
I hope the xml is the response from url, just like .post(url,data,function(xml){}) in jQuery.

The xml string can be extracted from xml.xmlDoc.responseText or xml.xmlDoc.responseXML.xml

Thanks a lot for the information. I didn’t find this in any other place!