1 <layers>

     2   <visual>

     3     <param name="opacity" type="anim">

     4       <duration>0.2</duration>

     5       <style>linear</style>

     6       <keyframe at="0.0">0.5</keyframe>

     7       <keyframe at="1.0">1.0</keyframe>

     8     </param>   

     9   </visual>

    10 </layers>