In most file systems, the following character is generally acceptable to use in a filename:
–(en dash or hyphen)
The other characters listed are typically not allowed in filenames:
?(question mark) is often used as a wildcard in query strings.%(percent sign) can be used in URL encoding but is generally not permitted in filenames./(forward slash) is used as a path separator in many operating systems and is not allowed in filenames.
Always make sure to check the specific rules of the file system you are using, as they can vary.