Well it is when it divides one class from another. Certainly has always been clear to me that the line is drawn at the first curtain you encounter when leaving your cabin class. As for the signs they point clearly to the rear of the aircraft only ie |_> if that makes sense. There is no arrow that suggests you go through the curtain to first and then back again. The sign above the aft suggesting a lav at the front right is not illuminated although I think it used to be but they have changed this sometime ago.