Winegard 3rd coax connection: Is it an input or output?

I was wondering if the unused 3rd coax connection on the backside of the Winegard 12volt/coax receptacle (see pic) is an input or an output.

My common sense understanding is that one connection is an input from the rooftop antenna, and the other one would be an input from the outside park cable hookup. I could be wrong.

The reason I ask, is my trailer had the radio removed when I purchased it. I bought a radio/dvd player with an integrated tv tuner built into it also. I just need to input to it thru a coax connection. If this 3rd coax connection on the backside of the winegard outlet was an output, like to a secondary television, it would make my life simple. That way, I could input to the tv tuner either thru antenna or cable. I could also listen to a television thru the built in radio speakers. I am modifying where the phone jack is with another wallplate that will accept RCA jack outputs from the radio to whatever televsion I use.

Does anyone know if this other connection is an output or input..........or have any advice on what I am attempting to do?

http://www.bossaudio.com/main/529

Thanks

Alright, I found the answer in another forum that B & D had posted in. Thanks for the diagram. It DID let me know that the 3rd connection is indeed an output for another tv set. I'm headed outside to wire eveything now.

http://winegard.com/mobile/pdf/2452013.pdf