protected $validFields = array(
        //order
        "MERCHANT" => array("type" => "single", "paramName" => "merchantId", "required" => true),
        "ORDER_REF" => array("type" => "single", "required" => true),
        "ORDER_DATE" => array("type" => "single", "required" => true),
        "ORDER_PNAME" => array("type" => "product", "paramName" => "name"),
        "ORDER_PCODE" => array("type" => "product", "paramName" => "code"),
        "ORDER_PINFO" => array("type" => "product", "paramName" => "info"),
        "ORDER_PRICE" => array("type" => "product", "paramName" => "price", "required" => true),
        "ORDER_QTY" => array("type" => "product", "paramName" => "qty", "required" => true),
        "ORDER_VAT" => array("type" => "product", "default" => "0", "paramName" => "vat", "required" => true),
        "PRICES_CURRENCY" => array("type" => "single", "default" => "HUF", "required" => true),
        "ORDER_SHIPPING" => array("type" => "single", "default" => "0"),
        "DISCOUNT" => array("type" => "single", "default" => "0"),
        "PAY_METHOD" => array("type" => "single", "default" => "CCVISAMC", "required" => true),
        "LANGUAGE" => array("type" => "single", "default" => "HU"),
        "ORDER_TIMEOUT" => array("type" => "single", "default" => "300"),
        "TIMEOUT_URL" => array("type" => "single", "required" => true),
        "BACK_REF" => array("type" => "single", "required" => true),
        "LU_ENABLE_TOKEN" => array("type" => "single", "required" => false),
        "LU_TOKEN_TYPE" => array("type" => "single", "required" => false),

        //billing
        "BILL_FNAME" => array("type" => "single", "required" => true),
        "BILL_LNAME" => array("type" => "single", "required" => true),
        "BILL_COMPANY" => array("type" => "single"),
        "BILL_FISCALCODE" => array("type" => "single"),
        "BILL_EMAIL" => array("type" => "single", "required" => true),
        "BILL_PHONE" => array("type" => "single", "required" => true),
        "BILL_FAX" => array("type" => "single"),
        "BILL_ADDRESS" => array("type" => "single", "required" => true),
        "BILL_ADDRESS2" => array("type" => "single"),
        "BILL_ZIPCODE" => array("type" => "single", "required" => true),
        "BILL_CITY" => array("type" => "single", "required" => true),
        "BILL_STATE" => array("type" => "single", "required" => true),
        "BILL_COUNTRYCODE" => array("type" => "single", "required" => true),

        //delivery
        "DELIVERY_FNAME" => array("type" => "single", "required" => true),
        "DELIVERY_LNAME" => array("type" => "single", "required" => true),
        "DELIVERY_COMPANY" => array("type" => "single"),
        "DELIVERY_EMAIL" => array("type" => "single"),
        "DELIVERY_PHONE" => array("type" => "single", "required" => true),
        "DELIVERY_ADDRESS" => array("type" => "single", "required" => true),
        "DELIVERY_ADDRESS2" => array("type" => "single"),
        "DELIVERY_ZIPCODE" => array("type" => "single", "required" => true),
        "DELIVERY_CITY" => array("type" => "single", "required" => true),
        "DELIVERY_STATE" => array("type" => "single", "required" => true),
        "DELIVERY_COUNTRYCODE" => array("type" => "single", "required" => true),
    );