Specifying a url for a dhtmlxtree node

Is there a way in the XML to specify the url for each node in the tree and access that information in script through the API?

I could have the item defined in the XML like this:

<item text="Catholic News Agency" id="cna" im0="iconText.gif" im1="iconText.gif" im2="iconText.gif" url="http://catholicnewsagency.com">

Then in the script. I could get the url like this:

var url=item["url"];

Tell how I could store and retrieve that data.