} // !FromString()

        public static string EnumToString(this DeliveryDateTypes c)
        {
            switch (c)
            {
            case DeliveryDateTypes.RequiredDate: return("optional");

            case DeliveryDateTypes.FixedDeliveryDate: return("fixed");

            default: return("");
            }
        } // !ToString()
        public static DeliveryDateTypes FromString(this DeliveryDateTypes _, string s)
        {
            s = s.ToLower().Trim();
            switch (s)
            {
            case "optional": return(DeliveryDateTypes.RequiredDate);

            case "fixed": return(DeliveryDateTypes.FixedDeliveryDate);

            default: return(DeliveryDateTypes.Unknown);
            }
        } // !FromString()