the unix-y preferences are generally handled by the "defaults" system, which is a fancy name for a folder of those com.something.whatever.plist files. Many automatic cocoa things like windows and open/save dialogs store their own preferences there. For apps not written specifically for OS X (classic and windows ports), it is not uncommon for them to have already duplicated this functionality by writing their own text file to store their prefs. So if you're writing a program and you make an NSWindow with an autosave name, the NSWindow will write it's position to the defaults database, which creates a plist file. Then the app writes its own preferences the way it did in OS 9, by creating a text file, and that's how you get two preferences files for each app. I assume