Some kinds of files are such that their names should not exceed 8 characters. Some others do not have such a limitation. Right?

Now, since I don't exactly know which files do and which files do not have that restriction, I always play safe and keep dubbing my files with less than 9 characters. This, however, has gradually become very frustrating, because I'm aware that in many cases my caution is not necessary.

Can anyone give a list of the kinds of files which necessarily need to be dubbed with less than 9 characters?

As far as I know all files that the game engine will end up using need to be 8 characters or less.

Files that are only used by weidu can be more than 8 characters.

For example the file "myadditiontoAr2000.baf" being APPENDed to ar2000.bcs would be okay because it is used only by weidu and the file the info ends up in is ar2000.bcs which follows the 8 character limitation. Likewise .d dialog files used by weidu can be longer than 8 characters so long as the dlg file being created for use in game is 8 characters or less.

Note: I have never had any problems with filenames used in this fashion. Whether this is the case or not for others I do not know. Most modders tend to stick to 8 characters just to avoid problems due to human error.