First Floor Closed officially Codifed
Seems like they are putting the official stamp on it. Tbh I thought they were gonna move away with it due to hidden but I guess not.
Rule image posted in comments.
Edit: it's come to my understanding that across the pond, the ground floor is what is considered the 1st floor in the US. So yes when people say FF(first floor) closed it generally means the ground floor. Sorry for that mix up