can't use xmlUrl name as atrribute in OPML output

In the opml spec, you can have an atrribute called "xmlUrl" to point to an rss feed, like this:

http://webaim.org/blog/media/blogroundup.opml

So for Views Datasource, you make sure you create a label for your fields so that they show up as the attribute title for your outputted xml, opml etc. Works great, but for some reason, when I have xmlUrl as my label, the opml that comes out of Views Datasource is not what I had hoped for. The attribute xmlUrl is coming out as just Url. So, instead of:


xmlUrl="http://blindaccessjournal.com/atom.xml" htmlUrl="http://www.blindaccessjournal.com/"


I am getting this:


Url="http://blindaccessjournal.com/atom.xml" htmlUrl="http://www.blindaccessjournal.com/"


Any ideas why the label xmlUrl is getting, I'm presuming, sanitised?