I think it means there is no backwards. If you’re going down the stairs, stop and turn around, you’re facing forward in the up direction. You could walk backward on stairs but not stand backward.
But, this is true of most places you stand. Sidewalks, middle of your living room, in a park. You can only stand backwards in places that have a specific direction to stand, such as in a line, an elevator, a classroom.
I think it means there is no backwards. If you’re going down the stairs, stop and turn around, you’re facing forward in the up direction. You could walk backward on stairs but not stand backward.
But, this is true of most places you stand. Sidewalks, middle of your living room, in a park. You can only stand backwards in places that have a specific direction to stand, such as in a line, an elevator, a classroom.