Sounds like a "bellybutton" for a take down line.
Does this sail stow into a sock or tube on deck? If so, the take down line would lead through the sock from the cockpit, out the front of the sock and up to that attachment point on the sail. During a takedown the tack , sheet and halyard are released and the sail sucked into the sock with the take down line.
Perhaps that's what you're looking at. I'm not familiar with that boat design.
EDIT: just took a look at what a CP 16 is - you probably won't have the sock/tube, but the take down line can still be used if you don't have a snuffer, or if you have difficulty dousing the sail without it.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Last edited by Faster; 04-15-2008 at 11:00 AM.