[DOCUMENATION] [QUESTION] Purpose of uDMA QSPI Full-Duplex Command

In the QSPI documentation, this notice is at the bottom of the implementation section:

https://github.com/openhwgroup/core-v-mcu/blob/12bc79e8b2fd4975db1d998a00a936b5ff5bd3d9/docs/doc-src/ip-blocks/udma_qspim.rst?plain=1#L40

Does this apply to both single-bit SPI and QSPI? If so, why is there a command in the control buffer section to enable full-duplex? Does this expect that a configured buffer can be used for both TX and RX? How is this specified?

https://github.com/openhwgroup/core-v-mcu/blob/12bc79e8b2fd4975db1d998a00a936b5ff5bd3d9/docs/doc-src/ip-blocks/udma_qspim.rst?plain=1#L276-L286