Short story, Trigger Inversion is where we make those analog Triggers accept On/Off functions of a momentary contact switch, such as Arcade push button. Called that as you are litterally inverting the signal.
Here is the OLD thread that covers this, but the images are long since been broken.
Be honest with you if you haven’t purchase your pad yet (or at least taken it apart) you are better off with a GamePad that DOES NOT have the Trigger Buttons wired as analog, like a Fight Pad or one of the Many Replacement PCBs that use Screw Terminals. The PS360+ or the Brooks Universal Fight PCB are your Best options for the mod (but they are going to cost more).
Update
I did find an image that relates to the thread with a wiring diagram
Thanks it’s long been gutted since I used it for my first stick a while back. I’m moving from 6 to 8 face buttons so I wanted to try using the triggers, but since the have a separate ground I’ll just use down click for the analog sticks.
Okay, I’m planning a project box style smashbox and that would have helped with figuring out analog stick support with padhacks like on Xbox 360 and ps2.