I have read the manual 10 times, checked the Onkyo site, and Googled the hell out of this, but I can't find a thing about it. The port with the red circle around it in the image is clearly not a blank, but is not mentioned in the text, and has no corresponding button on the remote. Although it appears clearly in the manual, it gets not a jot of a mention. I'm one of those guys that HAS to know what everything is for...The system is setup, works perfectly and is the hub for all my devices. HDMI ports 1-4 all happily occupied. Can somebody put me out of my misery and tell me what the extra HDMI port is for? It's driving me nuts! It's lousy labelling, but it's an engineers programming port! The white label refers to the port to the left, which is the assignable OUTPUT socket. Seems this had a lot of people very confused...They should have put a cover over it at least.