>>>>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.
>>
>>You're right! 60 million it is, then.
>
>Add a few more characters to the base, which are allowed in Windows - parentheses, space, underscore, ampersand, perhaps brackets and braces... it grows.

For me the "probably no trouble in other systems" rule only adds underscore to those 36 chars.