ModMan intake Oil filler / PCV port?

That's my intake/manifold air temp (IAT) for my fuel injection. I'm running a Megasquirt setup and needed to put one in since I don't have one built into the throttle body. I'm using a speed-density tuning setup instead of mass air flow. Alternatively, I think that port might be intended as a vacuum source for stuff like power brakes, but since I have manual brakes I used it for the IAT probe.