<?xml version="1.0" ?>
<sdf version='1.7'>
  <model name="model_frame_invalid_attached_to_cycle">
    <link name="L"/>
    <frame name="F1" attached_to="F2"/>
    <frame name="F2" attached_to="F1"/>  <!-- INVALID: graph cycle between F1 and F2. -->
  </model>
</sdf>
