The Mini Round 3-Pin SPDT ON-OFF Rocker Switch is designed as a Single Pole Double Throw . This means it has one input (the switch itself) and two outputs. This is commonly used as an "on/off" function. In this case, there are two "on" functions, and one "off" function.
DP/LS/RS Lockout Function
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. 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.
Use of the DP/LS/RS Switch Harness allows you to connect the 3-way rocker switch to a Brook PCBs 4-pin male connector, enabling you to switch between these modes.