timing                                             Specifies when stimulus
                                                   arrives at port or
                                                   internal net. To specify
                                                   bidirectional I/Os,
                                                   specify the same port
                                                   name for both arrival and
                                                   required time
                                                   constraints.
 { -arrival                                          Use to specify data
                                                     arrival time at a path's
                                                     input.
   | - required }                                    Use to specify data
                                                     arrival time at a path's
                                                     output.
 [ -g | signal_list]                                 Applies constraint
                                                     globally, to a wire, or
                                                     to ports in a module or
                                                     instance/all ports of
                                                     appropriate type at the
                                                     current scope
 { -rise                    rise                     Specifies a single rise
                                                     time for the data.
   | -minrise               min_rise                 Specifies a minimum rise
                                                     time for the data.
     -maxrise               max_rise }               Specifies a maximum rise
                                                     time for the data.
 { -fall                    fall                     Specifies a single fall
                                                     time for the data.
   | -minfall               min_fall                 Specifies a minimum fall
                                                     time for the data.
     -maxfall               max_fall }               Specifies a maximum fall
                                                     time for the data.
 [ - clock                  clock                    Specifies the clock to
                                                     which the rise and fall
                                                     constraints are
                                                     relative.
 [ -edge                    r | f ]                  Specifies whether the
                                                     rise and fall constraints
                                                     are given relative to the
                                                     rising edge (r) or the
                                                     falling edge (f) of the
                                                     clock / r
