19.1.3 Opening a Tape File for Input
  To open an existing magnetic tape file, you also use the OPEN
  statement. For example, the following statement opens the
  file PAYROLL.DAT. If you do not specify a record size or a
  block size, BASIC defaults to the values in the header block.
  If you do not specify a record format, BASIC defaults to the
  format present in the header block (ANSI F or ANSI D). You
  must specify ACCESS READ if the tape is not write-enabled.
  For example:
  100 OPEN "TAPE:PAYROLL.DAT" FOR INPUT AS FILE #4%
                        ,ACCESS READ