NTFS has the same two restrictions that many UNIX file systems have, NUL and slash. The APIs, Win32 in the case of [1], have further restrictions. If you want

NTFS has the same two restrictions that many UNIX file systems have, NUL and slash. The APIs, Win32 in the case of [1], have further restrictions. If you want you can use a different API/personality and write whatever value you'd like (sans NUL and /) provided said personality has no limits -- NTFS does no validation itself. In practice, Win32 being the default personality makes said plethlora of restrictions true, but it isn't a "filesystem" limitation, rather an API restriction. A nuanced if unimportant difference.