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.