Post #1826126

@jak2k They can include everything except slashes. Some filesystems offer further restrictions, though, and macOS requires a filename to be a valid UTF-8 stream (which it then normalises to NFD, so what you get back from directory listing might not be bytewise equivalent with the name of the file you created, as is the case in other Unixen). macOS also does case insensitivity, unlike most Unixen, although it has been optional for a long while now.