OK, so I have a PCB from VFX and I'm completely in the dark on some of what the holes are for. I completely understand the resistors and LEDs. I THINK I understand the on/off switch. What I don't get are the +/- 9V in/out slots. I've circled them dark/light blue and dark/light red. Can anyone shed some light on these for me? Also, this isn't the EXACT PCB that I have, but fairly close, close enough to get the general idea.