/// <summary>
        /// TBD ?!?
        /// </summary>
        public override string WfsXmlRepresentation()
        {
            string strOperationType = GetWFSOperationTypeString();
            string strLeftOperand   = LeftOperand.WfsXmlRepresentation();
            string strRightOperand  = RightOperand.WfsXmlRepresentation();
            string str = "<ogc:" + strOperationType + ">" + strLeftOperand + strRightOperand + "</ogc:" + strOperationType + ">";

            return(str);
        }