extra_messages_xml

<?xml version='1.0'?>
<mavlink>
  <include>common.xml</include>
  <include>ardupilotmega.xml</include>

  <enums>
    <enum name="CAM_MSGS">
      <entry name="CAM_PING" value="0"><description>Ask if the camera is alive.</description></entry>
      <entry name="CAM_ACK" value="1"><description>Reply from the camera</description></entry>
    </enum>
  </enums>

  <messages>
    <message id="240" name="CAM_MSG">
      <field type="uint16_t" name="type" enum="CAM_MSGS">Camera message ID as specified by CAM_MSGS enum.</field>
      <field type="uint8_t" name="sequence">Sequence number for camera message, so we don't do things out of order.</field>
    </message>
  </messages>

</mavlink>