// Create the XmlNamespaceManager.
NameTable nt = new NameTable();
XmlNamespaceManager nsmgr = new XmlNamespaceManager(nt);
nsmgr.AddNamespace("rk", "urn:store-items");
// Create the XmlParserContext.
XmlParserContext context = new XmlParserContext(null, nsmgr, null, XmlSpace.None);
// Create the reader.
XmlReaderSettings settings = new XmlReaderSettings();
settings.ConformanceLevel = ConformanceLevel.Fragment;
XmlReader reader = XmlReader.Create(new StringReader(xmlFrag), settings, context);