The XML starts with
<edmx:Edmx Version="1.0" xmlns:edmx="http://schemas.microsoft.com/ado/2007/06/edmx"><edmx:DataServices m:DataServiceVersion="1.0" m:MaxDataServiceVersion="3.0" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
so one way to access the attribute of each DataServices
element is
XmlNamespaceManager nsMgr = new XmlNamespaceManager(navigator.NameTable);
nsMgr.Add("edmx", "http://schemas.microsoft.com/ado/2007/06/edmx");
foreach (XPathNavigator dataServices in navigator.Select("edmx:DataServices", nsMgr))
{
string version = dataServices.GetAttribute("MaxDataServiceVersion", "http://schemas.microsoft.com/ado/2007/08/dataservices/metadata");
}
If you want the attribute value of the first such attribute then doing
nsMgr.Add("m", "http://schemas.microsoft.com/ado/2007/08/dataservices/metadata");
string version = navigator.SelectSingleNode("//edmx:DataServices/@m:MaxDataServiceVersion", nsMgr).Value;
should suffice.