Wow. I checked the main file and it's real. Thanks for enlight me @Mcgan. It's fun to discover somethings outside the gameplay. I have a question how can we add custom icon now? Since the icon is "icon = GFX_army_type_defensive" now, it's a word now, not number, does that meant that i must name somethings in the other file?The way icons work has changed in 3.1, if you look in the game files, you'll see that "icon_frame =" doesn't exist anymore and has been replaced with "icon =".
Same with ships.