I am confused at how people describe gender roles and their trope classification in anime. I understand that traps are characters appearing to be girls but are actually guys. One of my favorite traps of all time is Steins;Gate's Ruka Urushibara.
However, I don't get what "reverse traps" are. Are they appearing to be traps but are actually legit girls (a trap trap)? Or a character that initially appears to be a boy, but is actually a girl (a girl trap)? For clarity, consider what you would call Charlotte (Charles) Dunios from Infinite Stratos.
EDIT: This post is not intended to be offensive to other genders in any way, the naming convention of "traps" pertain to fictional characters in anime/manga only.