95 civic halo headlights issue

I never noticed this before but on almost all the halo headlights for the 92-95 civic has 3 ports, one for a bulb, one for a projector, and one for a signal bulb, but im confused. why are there 3 ports if the civic only has to bulbs? would you have to splice the wires and ad in a new bulb? Can someone get back to me on this?

the third socket are for "city lights" these are lights that would be always on, you can also just use them as a turn signal, if you splice wires from the turn signal wires to them.