Why are many enums not implemented in the drivers (adi_spi_bf6xx.h)?

I'm using ADSP-SC573 EZ-board.

When I look in adi_spi_bf6xx.h there are many enums that are not implemented, for example ADI_SPI_RX_MODE.

Will they ever be implemented? Why not delete them if not?

I snippet from adi_spi_bf6xx.h:

/*!
 *  Enumeration for the SPI transceiver mode.
 *  The SPI can be configured to operate in numerous modes that determine the SPI data direction and also the
 *  width of the SPI serial data bus.  The width of the SPI serial data bus can be set to single, dual or
 *  quad i/o mode.  In single i/o mode, the traditional standard SPI mode, data is sent and received via the
 *  MOSI and MISO serial data lines.  In dual i/o, the SPI serial data lines can be configured as either
 *  2 tx serial lines or 2 rx serial lines.  In quad i/o, the SPI serial data lines can be  configured as either
 *  4 tx serial lines or 4 rx serial lines.
 *
 */
typedef enum
{
    ADI_SPI_TX_MODE,                                           /*!< Not implemented                             */
    ADI_SPI_RX_MODE,                                           /*!< Not implemented                             */
    ADI_SPI_TXRX_MODE,                                         /*!< SPI with MOSI and MISO, single i/o mode     */
    ADI_SPI_TX_DIOM_MODE,                                      /*!< Tx Dual I/O, dual i/o mode                  */
    ADI_SPI_RX_DIOM_MODE,                                      /*!< Rx Dual I/O, dual i/o mode                  */
    ADI_SPI_TX_QSPI_MODE,                                      /*!< Tx Quad SPI, quad i/o mode                  */
    ADI_SPI_RX_QSPI_MODE,                                      /*!< Tx Quad SPI, quad i/o mode                  */
    ADI_SPI_FAST_MODE,                                         /*!< Not implemented                             */
    ADI_SPI_DISABLE_TX,                                        /*!< Not implemented                             */
    ADI_SPI_DISABLE_RX,                                        /*!< Not implemented                             */
    ADI_SPI_DISABLE_ALL                                        /*!< Not implemented                             */
}ADI_SPI_TRANSCEIVER_MODE;