What characters are invalid (or valid if that's easier) in POI CSV filenames?

Microsoft -> Filename is Invalid or Cannot Contain Any of the Following Characters
http://support.microsoft.com/kb/177506
"A filename cannot contain any of the following characters: \ / : * ? " < > |"

For simplicity and to avoid issues with Linux or Apple, just use letters and numbers. Avoid the use of the space character too.

I'm currently replacing all non-word characters with an underscore. Is that a safe character or should I remove them as well?

Thanks!

That'd work quite well, but a concern, albeit a very small one, is that underscores tend to get lost in the translation when writing them down.

You can use _ ( ) - be careful with this one ~ it doesn't play well in excel.

My code uses this regular expression to replace everything: /\W|__+/ so I think I have my bases covered now.

http://gist.github.com/470079#LID165