Peugeot 206 Gearbox: Parts & Repair

hello,

I'm looking for the oil filler opening for the gearbox on a Peugeot 206 2.0 HDI, manufactured in 2003.
It's supposed to be located on the lid, on the wheel arch side. Unfortunately, I can't find any screws there at all.

Therefore, my question is: Has anyone ever checked the oil level before, or does anyone have information about the exact location of the screw?

Thank you for your replies.