Though fighting games will not make much use of the analog sticks that a gamepad commonly possesses, there are times where it is still helpful to access them when a game requires these controls to work. Of those modes are DP, LS, and RS. This harness allows you to connect a DPDT (Double Pole Double Throw) 3-way rocker switch to a Brook PCBs 4-pin male connector, enabling you to switch between these modes.
DP, LS, and RS Explained
DP is "D-Pad". This is the common mode you will use for most arcade style games. You will almost always have this mode set when playing fighting game titles. LS represents "Left Stick". Some games will not make use of the D-Pad and instead require you to control using the left-stick. RS, or "Right Stick" is rarely if ever used for sole control, but functions in the same manner as LS for the right analog stick.
The illustration below offers suggested wiring install. If you flip the wiring so that LS is instead the red wire and RS is the green wire, please flip the connector as well.