why does my jamma harness have 2 wires off of cc (p2 button4)?

[runawayabc123]

I got this jamma harness: http://www.jammaboards.com/store/jamma-harness/prod_146.html

It has a white wire and a gray wire off of "cc" (player 2 fire button 4).  Does anyone know why?  It was put with the speakers and coin operation wires (some came a little zip tied together, not that I put any faith in that and double checked everything). 

[MonMotha]

Some games have been known to use that input for a second test or service credit button.  The Neo-Geo single slot uses it (and its player 1 equivalent) for button 4.  It's not generally necessary.