xilinx/xc7/empty.xml

<empty>
   <input  name="DUMMY_I" num_pins="1" />
   <output name="DUMMY_O" num_pins="1" />
   <interconnect>
   </interconnect>
   <pinlocations pattern="spread_perimeter"/>
   <fc in_type="frac" in_val="1.0" out_type="frac" out_val="1.0" />
</empty>