public XmlDsigFilterTransform(string xpath, XmlDSigFilterType filter, Dictionary <string, string> namespaces = null) : this()
        {
            XmlNamespaceManager nsMgr = new XmlNamespaceManager(new NameTable());

            if (namespaces != null)
            {
                foreach (KeyValuePair <string, string> ns in namespaces)
                {
                    nsMgr.AddNamespace(ns.Key, ns.Value);
                }
            }
            _elements = new XmlDsigFilterElement[] { new XmlDsigFilterElement(xpath, filter, nsMgr) };
        }
 public XmlDsigFilterElement(string xpath, XmlDSigFilterType filter, XmlNamespaceManager nsMgr)
 {
     _nsMgr  = nsMgr;
     _xpath  = xpath;
     _filter = filter;
 }