IEnumerable<XamlXmlNodeInfo> ReadXData ()
{
var xt = XamlLanguage.XData;
var xm = xt.GetMember ("Text");
yield return Node (XamlNodeType.StartObject, xt);
yield return Node (XamlNodeType.StartMember, xm);
yield return Node (XamlNodeType.Value, r.ReadInnerXml ());
yield return Node (XamlNodeType.EndMember, xm);
yield return Node (XamlNodeType.EndObject, xt);
}