SPI bus / CS pin sketch name?

I have been trying to use the SPI bus with my M2 with no success for now. On the 26 pin connector the MISO, MOSI and CLK seem to work but I have a problem with the CS.

In the docs the CS is refered to be on pin 15 as SPI0 CS/USART2RX. On the pin mapping page, the name given to use in the sketch is SPI0_CS1 but it doesn’t work (neither SPI0_CS0). What is the right name to use?

Thanks,

Jean