iMac (24 inch, mid-2007) has a port not identified in article. Can this iMac be used in target display mode?

My iMac (24 inch, mid-2007, 4 GB RAM) has a port that is not identified in this article. Looking at the back of the Mac, it is the farthest right port. The shape of the port is a rectangle (taller than it is wide) with about 16 pinholes in it. The symbol above it is a rectangle with rounded corners (like a TV screen) with one vertical line on either side of it.

I wonder if I can use this old iMac in "target display mode" with a new iMac.

Edit: I reread the article; my old iMac does not support Target Display Mode. Still curious about the port, but it is not urgent.

Message was edited by: GPayne