In kill confirm, it is collecting the dog tags that count towards the winning scores.
After making a kill and in order to win, you could say it is mandatory to collect the dog tag in order to make it counts.
In this map, I tried locking down in the power station and this let me make a lot of kills but it will not contribute to winning the game. Your opponents are locked outside but they are denying all your kills by collecting the tags themselves.
Mode: Kill confirm in Comeback
Weapons: Bal27 with Autofocus