51 46 013 Removing And Installing/Replacing Rear Window Roller Blind
WARNING: This page is about a different car, the 2008 BMW Alpina and 2007 BMW Alpina. However, it is still accessible from the selected car via links, so may be relevant.
Operation is described in:
Removing and installing/replacing trim for oddments tray (back shelf) . See 51 46 000 REMOVING AND INSTALLING/REPLACING TRIM FOR REAR PARCEL SHELF .