Shutter switch cable connection in Germany

Everywhere I research I read about 3 cables connecting to a roller blind switch. The Auf, Ab and Live (Up, Down and "L").

What is the 4th cable (plugged in 12mm?) on my roller blind switch for? Where can I find out more info about it? I think the hardware is GIRA.

Thanks for your fast reply!

Ok. I had a look behind another roller blind switch and there too seem to be 2 power cables coming to the switch (2 blue, 2 brown, 2 earth). Going up from the switch to a box near roller blind engine is a cable with 5 wires: earth, blue, brown, black and grey (not used).

So the grey can be used to provide the live (L) to the Shelly 2.5 at the top the, right?

Would they have provided 2 blue, 2 brown and 2 earth coming to the switch just for future automation?

Yes, it was a bit hard to understand.

The first diagram is how the wiring is before installing the Shelly 2.5. The second one is how I believe it should look like once installed.