Curious elevator button

While I was getting out of the Lassonde building I took a closer look at the elevator buttons and saw this:

Photograph of elevator buttons found in the Lassounde building at York University. The embossed type on button for the ground floor (upper right) says ☆G but the braille says “main”.

What caught my attention was the braille. I’ve seen buttons with star signs before, and what I’d been seeing had been having the star sign “translated” to the letter S—odd to me, but if this is an actual convention then actual blind people probably aren’t going to get confused. However, the first letter for the “ground floor” button was clearly not an S.

So what is it? I took some time trying to decipher it and found that it read “main”. So to a blind person, the building doesn’t have a “ground floor,” but a “main floor.”

I don’t know how others feel, but I think this is an inconsistency.