Forbidden Characters and Filenames
This comes from Propellerhead’s Trivia Department, but it’s worth remembering, if Windows tell you off, or stops you doing something, without telling you why. There are a number of little-known restrictions on characters and names that you are allowed to use when naming folders or files.
Most of the restrictions hark back to the olden days of DOS and UNIX, and quite honestly the chances of you wanting to use any of them are fairly remote, but here goes.
The characters that you are not allowed to use in folder or filenames are: / : * ? " < > |, and if you try Windows will bleep at you.
The following is a list of names that you are not allowed to use: CON, PRN, AUX, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9.
This time Windows will let you enter the name but as soon as you press Return it will revert to its former name.
Before anyone writes in, yes we know there are ways to defeat the system, but it’s really something only industrial-strength geeks would be interested in… Don’t forget there are hundred more great tips and tweaks in the archive at PCTopTips
