A friend asked me to identify an element, but I have no idea either. Customary search on BrickLink modified bricks/plates/tiles categories didn't give results. I do not have any additional information besides this picture.
This looks like Plate, Modified 2 x 8 with Door Rail in yellow.
It's not easy to find because you would think it's a 1x8 plate modified rather than a 2x8.
Additional link: Plate, Modified 2 x 8 with Door Rail at rebrickable.
Also, looked over it because it's in black... just a smudge on my cellphone for my poor old eyes Feb 11, 2020 at 15:04