PINOUT XONAR DX

Hi everyone,
Does someone knows the meaning of those not used but connected pinout ? (in the green rectangle)
Or where Can I find the shematic for it?



I'd like to get the 4 Spdif stereo OUT (FRONT, SIDE, BACK, SW/C) like I was able to do it on Creative Sound Blaster following this shematic (Spdif0 OUT, Spdif1 OUT, Spdif2 OUT, Spdif3 OUT) :



Thanks for any help !