OK I have a flashcard called 3dstt from www.n3dstt.com. It runs on my dsi xl (with version 1.42) and 3ds (with version 2.1.0-4U).
Some of the menu files and folers are:
_DS_MENU.DAT
__rpg (inside this folder I have cheats, fonts, icons, language, ui folders and globalsettings.ini, lastsave.ini...