VMS Help FORTRAN, Statements, BACKSPACE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Repositions a sequential file that is currently open for sequential
  access to the beginning of the preceding record.  The file must be
  on disk or tape.  Statement format:

     BACKSPACE ([UNIT=]u[,ERR=s][,IOSTAT=ios])
     BACKSPACE u

      u     Is an integer variable or constant specifying the
            logical unit number of the file, optionally prefaced
            by UNIT=.  UNIT= is required if unit is not the
            first I/O specifier.
      s     Is the label of a statement that receives control
            if an error occurs, prefaced by ERR=.
      ios   Is an integer variable to which the completion status
            of the I/O operation is returned, prefaced by IOSTAT=
            (positive if an error occurs, zero if no error occurs).

  A BACKSPACE statement should not be specified for a file that is
  open for direct or append access.  Backspacing from record "n" can
  be done by rewinding to the start of the file and then performing
  n-1 successive reads to reach the previous record.  For direct and
  append access, the current record count ("n") is not available to
  the Fortran I/O system.