I used to love the fact that I could put just about any character in a file name is OS 9. With UNIX as a base, it appears that there are a few restrictions to naming files.
I know that in Windows (at least NT), if you use illegal characters in a file name, you will get a cryptic message about saving the file (can't remember what it is now...I try to forget I have to use 'doze at work).
I just noticed today, saving a web page out of Safari onto my iDisk, that when I try to put in a forward slash (/), Jaguar automatically changes that to a dash (-) in real time as I'm typing it! Personally I like that much better than having to figure out if there is some problem other than a simple character change.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030205062725727