xilinx/common/primitives/iob33/modes/no_obuf.xml

<mode name="NO_OBUF" xmlns:xi="http://www.w3.org/2001/XInclude">
  <xi:include href="../outpad.pb_type.xml"/>
  <interconnect>
    <direct name="O" input="IOB33_MODES.O" output="outpad.outpad">
      <metadata>
        <meta name="fasm_mux">
          IOB33_MODES.O : PULLTYPE.NONE,LVCMOS33_LVTTL.DRIVE.I12_I16,LVCMOS12_LVCMOS15_LVCMOS18_LVCMOS25_LVCMOS33_LVTTL_SSTL135_SSTL15.SLEW.SLOW
        </meta>
      </metadata>
    </direct>
  </interconnect>
</mode>