Does the bottom lip of a window AC unit go in FRONT of the window sill area or BEHIND it?

I have an AC unit [looks similar to this]


http://www.amazon.com/Frigidaire-FAC126P1A-Conditioner-Electronic-Controls/dp/B000Q7IGX0





The bottom has a metal bracket that goes along the AC unit and the top does too. I have the top one in FRONT of the window thats down, and the bottom metal lip bracket thing is BEHIND the bottom of the window. Is this correct? It's level and doesn't look unsafe but I wasn't sure if this is correct or if I should have the bottom one in front as well.|||The top stays on the inside and the bottom goes on the outside|||This is the correct and most stable way to install a window AC whether it was the way the manufacturer intended it to be installed that way or not.