pathname: root-name root-directory relative-path
root-name: operating system dependent sequences of characters implementation-defined sequences of characters
root-directory: directory-separator
relative-path: filename filename directory-separator relative-path an empty path
filename: non-empty sequence of characters other than directory-separator characters
directory-separator: preferred-separator directory-separator fallback-separator directory-separator
preferred-separator: operating system dependent directory separator character
fallback-separator: /, if preferred-separator is not /