It is most certainly a interior counter extension. Look for brackets along your counter/drawer surface. We have never used ours.
We've had 2, 08 Flagstaff and the present 12 Flagstaff and both were for outside. IMO they are worthless as they are definitely not water resistant and even with our awning out all the time, the moisture gets to them. I finally took the hardware off of them and trash canned them.
My Roo only has one mounting place for this table. Its outside the door next to where the exterior propane line comes out. Its purpose is to support your needs for counter space while your grilling. It should fit on the same rail as the BBQ grill just outside the front door.
You're all wrong.. I know exactly what that is.... It's a knee table. When you need to do your "business", you flip that angled arm down.. pinch it between your knees and have a hands free table top for your preferred reading material.