The Sony Playstation 3 gamepad offers a left analog and right analog button. These are activated upon pushing in on the analog stick. The Playstation 4 introduced the touchpad, which is used for analog motion much like a mousepad. This also contains a button that you can push in. Street Fighter V utilized the Touchpad button for some features in training mode, among others. That is why the touchpad key is represented by a button control on Brook control devices such as the Universal Fighting Board and PS4+ with Sound.
With the 4-pin harness, you can now access those buttons. The .110 female connector will fit most Japanese style pushbuttons with a .110 terminal. The harness also possesses a 3 connection daisy chain that serves as a ground for each button.
The 4-pin connector is keyed, meaning it has grooves to prevent it being put on the wrong way. The only way it could be put in incorrectly is if the header was soldered on upside-down. The color guide below shows the color for the input signals for each button. The 4-pin has been given an extra ground connection to allow for custom builds requiring more space or perhaps the ground can provide button coverage out of reach of the main harness. If not needed, the excess quick disconnect can be unused or cut.