BCD 996XT C-CH Output Operation

Could someone explain this feature? The menu settings ask off, on or expand. Then choose front or back port? What do you do next? What is supposed to be used with the ports?



Is that similar to the Activity ID feature on the 250, 296, 780 and 796 has?



I have looked on the CD, the RR and in the printed manual I purchased but none explain this feature.



Thank you.

BCD 996XT C-CH Output Operation