The behavior of the wildcards changes slightly between source and target masks. Both the sourceMask and targetMask can contain * and/or ? wildcards. RENAME requires 2 parameters - a sourceMask, followed by a targetMask. No tests were done with unicode in file names. These rules were discovered after extensive testing on a Vista machine.

I figure many others may be interested in what I discovered) I got tired of not knowing the rules and decided to experiment on my own. (Yes - this is a case where I am posting a paired question and answer.

Of course knowing the rules would also benefit batch development. If I knew the rules for how wildcards are processed then I figure I could use the RENAME command more effectively without having to resort to batch as often. Frequently I've had to resort to writing a small batch script with a FOR loop that parses each name so that I can build each new name as needed. I haven't been able to anticipate what works and what doesn't. I've managed to successfully use wildcards in the filename2 parameter on some occasions, but it has always been trial and error. Not much help - there are many ways that statement can be interpretted. If you use wildcards in filename2, the characters represented by the wildcards will be identical to the corresponding characters in filename1.' 'You can use wildcards ( * and ?) in either file name parameter. Here is all it has to say regarding wildcards: The Microsoft technet XP online help isn't much better. The built in HELP facility is of no help - it doesn't address wildcards at all. How does the Windows RENAME (REN) command interpret wildcards?

Cmd rename multiple files