Is the city name an alias, a code name, or a real name?

Question

In One Punch Man, all city have some sort of name like A-City or Z-City, is this an alias, a code name, or a real name of the cities?

Answer 1

Well the anime and manga never explicitly states one way or the other but givin how all the characters refer to them in that manner I believe that's just how the cities are named.My evidence being that normal citizens refer to them as such implying that it is not a code name.