Unformatted I/O statements do not contain format specifiers and
  therefore do not translate the data being transferred.

  Unformatted I/O is especially appropriate where the output data
  will subsequently be used as input.  Unformatted I/O saves
  execution time by eliminating the data translation process,
  preserves greater precision in the external data, and usually
  conserves file storage space.

  Unformatted I/O statements do not specify a format (FMT=) in the
  control list (clist).  Other "clist" elements are required
  depending on the type of access.

  Unformatted sequential READ:

    READ (UNIT=u[,IOSTAT=ios][,ERR=err][,END=end]) [iolist]

  Unformatted direct access READ:

    READ (UNIT=u,REC=rec[,IOSTAT=ios][,ERR=err]) [iolist]

  Unformatted indexed READ:

    READ (UNIT=u,KEY=k[,KEYID=n][,IOSTAT=ios][,ERR=err]) [iolist]

  Unformatted sequential WRITE:

    WRITE (UNIT=u,[,IOSTAT=ios][,ERR=err]) [iolist]

  Unformatted direct access WRITE:

    WRITE (UNIT=u,REC=rec[,IOSTAT=ios][,ERR=err]) [iolist]

  Unformatted indexed WRITE:

    WRITE (UNIT=u[,IOSTAT=ios][,ERR=err]) [iolist]