Hi!
Quote from Excel Help under filenames:
File names cannot include any of the following characters: forwar
slash (/), backslash (\), greater-than sign (>), less-than sign (<)
asterisk (*), question mark (?), quotation mark ("), pipe symbol (|)
colon

), or semicolon (

.
Must say, the first time I read it it surprised me: it let me us
apostrophes, which was nice for pedantic punctuation!
Al