>>>>If we're talking about file names, some characters are not valid, and others are effectively duplicates e.g. "A" and "a" are the same because Windows file names aren't case sensitive.
>>>>
>>>>A better estimate is 10 digits 0-9 + 26 alphabetic chars, or 36 total chars.
>>>>
>>>>36^5 is about 60 million.
>>>
>>>I would agree with John R, you are not taking into account UNICODE support for the file names, or even simple valid characters like ñúóéáí etc. (oh, and the space!)
>>
>>The OP has only 5 chars/bytes of space for storage, so UniCode is out. If you want to include special characters like space, sure, that's to one's taste.
>>
>>As for ñúóéáí etc. - FireFox underlines it with a red squiggly line, has no idea what it is. Clearly people who have lived south of the Equator start writing strangely ;-)
>
>You meañ thè Frénçh, Spaniards and Italíans? Ør the Scandinavians, or the šłavič folksz, the Hűngárians or those remainders of ănçiênţ Řománs to my east?

They write strangely too ;-)