Rectangular hole in bottom of x280

[PaulosK]

There is a rectangular hole on the bottom of my x280, it doesn't connect to anything, it just exists. I just saw it 2 years later buying the laptop, I thought that there was a piece there that I lost, but no all the disassembly guides have this hole on the bottom, so either I am missing something or I am going insane, because this is the worse design flaw I have ever seen and I don't understand why would they put a 1*1 cm hole on the bottom of the laptop for no reason.
Does anyone know what's going on? If I have lost anything or if this is completely normal?

[RealBlackStuff]

You obviously never read the HMM (Manual).

[PaulosK]

You obviously never read the HMM (Manual).

No obviously I have never read the manual for a 200€ used laptop.
It's for a docking station.
This still doesn't explain why there isn't any protection and it is just a hole. There are 2 more for the docking station but these have protection. This is just a hole.

[TPFanatic]

There’s an even bigger hole on the opposite side of the laptop, with what looks like fan blades behind it.

Best keep it away from water.

[babblefish]

If I remember correctly, the open holes on the bottom are to allow any liquid spilled on the keyboard to drain away rather than remain inside the laptop.