Read about it here: https://www.wikiwand.com/en/Chevrolet_Citation#/X-11 What's kind of funny is that it says "11-X" on the driver's door, but it says "X-11" on the passenger door and steering wheel.
Someone must've been laying on the floor, looking upside-down at the door when they put it on. Kind of like Cary Grant in "Father Goose," with YNNEJ (supposed to have been JENNY).
Maybe it's just that famous GM quality control everyone raves about? Maybe it's actually a roman numeral "X"? It would be an 11-10 then....Oh the puns are endless.....
Just like the fog/driving lights under the bumper...at least point them in the same general direction.