Oil Drip (from bottom black tube)

[Lord Popgun]

Of course its in the manual. But the theory is not. You can google evaporative emission systems for more info as they all work kind of the same AFAIK

But, from the Honda Common Systems Manual, edited a bit:

Fuel vapor from the fuel tank is routed to the evaporative emission canister (EVAP canister) where it is absorbed and stored while the engine is stopped. When the engine is running and the evaporative emission purge control valve (EVAP purge control valve) is open, fuel vapor in the EVAP canister is drawn into the engine through the carburetor (ok, we don't have a carb so it most likely goes into the air plenum).

This is not new tech and has been around a long time. Cars have the same basic system.

Also, overfilling the tank can lead to saturation of the canister (charcoal) and that can cause problems, and drainage. Cars too...
Looking at the wiring diagram, the evap purge control valve is controlled by the ECM