◄Up► ◄Contents► ◄Index► ◄Back► ──────────────────────────────────────────────────────────────────────────── FORTRAN run-time error F6420 unknown unit number A statement such as BACKSPACE or ENDFILE specified a file that had not yet been opened. (The READ and WRITE statements do not cause this problem since, instead of generating this error, they prompt you for a file if the file has not been opened yet.) -♦-