System.Xml.XPath.XPathNavigator.LookupNamespace C# (CSharp) Method

        public virtual string LookupNamespace(string prefix)
        {
            if (prefix == null)
                return null;

            if (NodeType != XPathNodeType.Element)
            {
                XPathNavigator navSave = Clone();

                // If current item is not an element, then try parent
                if (navSave.MoveToParent())
                    return navSave.LookupNamespace(prefix);
            }
            else if (MoveToNamespace(prefix))
            {
                string namespaceURI = Value;
                MoveToParent();
                return namespaceURI;
            }

            // Check for "", "xml", and "xmlns" prefixes
            if (prefix.Length == 0)
                return string.Empty;
            else if (prefix == "xml")
                return XmlReservedNs.NsXml;
            else if (prefix == "xmlns")
                return XmlReservedNs.NsXmlNs;

            return null;
        }

		// FIXME: add a bunch of annoying datetime functions

		public static object FnResolveQName (string qname, XPathNavigator element)
		{
			if (qname == null)
				return null;

			int index = qname.IndexOf (':');
			string prefix = (index < 0) ? "" : qname.Substring (index);
			return new XmlQualifiedName (
				element.LookupNamespace (prefix),
				index < 0 ? qname : qname.Substring (index + 1));
		}