dft_scan_io                                        Selects one pair of scan
                                                   data input and output
                                                   signals.
 [ tree ]                                            Applies the constraint to
                                                     all levels of hierarchy
                                                     below the object(s)
                                                     specified.
 [ -scope ]                 scope                    design unit/ current scope
 -input                     signal
 -output                    signal
 -tristate                  [ yes | no ]              /no
