@LFN[filename]: Returns the long filename for a short ("8.3") filename. The filename may contain any valid filename element including drive letter, path, filename and extension; the entire name including all intermediate paths will be returned in long name format. If filename does not refer to an actual file, the results are unpredictable.
On an LFN drive, the returned name may contain white space or other special characters. To avoid problems which could be caused by these characters, quote the returned name before you pass it to other commands. See the notes under Variable Functions for additional details.
If filename is quoted, the returned filename will also be quoted (if necessary).