V4 Plastic Panel Above Rear Light

I noticed a plastic panel just below the pillion grab handle and above the rear light. It has quite a gap around the rear edge and looks like it should lift up? What's it for, how is it fixed? And before anyone shouts "RTFM!!" I did, but still could not spot anything. TIA.

 

This one. I was hoping someone was going to suggest a mass damper like the GP23 motogp bike

 

Radar is below the light

 

Thanks, so the diagram confirms its a cover, and it's screwed on from the bottom. Do we know what its covering?
Also, it shows the passenger handle unit is a huge robust lump on the end of the bike!