Since FTP is intended for use in a heterogeneous environment, User-FTP implementations MUST support remote pathnames as arbitrary character strings, so that their form and content are not limited by the conventions of the local operating system.
In particular, remote pathnames can be of arbitrary length, and all the printing ASCII characters as well as space (0x20) must be allowed. RFC-959 allows a pathname to contain any 7-bit ASCII character except CR or LF.