2012 was the year I believe. There are actually multiple float valves on top of the tank. There’s the regular inlet valve, usually on the tank, but sometimes it’s an inline valve in the fill neck. The inlet is typically near the front of the tank if packaging allows. Then in other places on the tank there’s the vent valve (middle) and a grade valve (rear) that acts as a backup vent valve for if the boat has a different attitude. The air side of the grade and vent valves are hooked together, so they serve the exact same purpose. On carbon canister systems, the air side of these valves are plumbed separately from the inlet. But on pressurized systems, they are plumbed back into the fill neck assembly. When liquid fuel fills up to the bottom of a float valve, it shuts off the vent to the air side. Automatic shutoff fuel nozzles will trip when either of these two occur: 1. The float valve on the inlet closes (or the inline flapper closes). 2. Both the vent and grade valves close, not letting any air escape the tank.