ardupilotmega.xml

<?xml version='1.0'?>
<mavlink>
     <include>common.xml</include>
     <!-- note that APM specific messages should use the command id
      range from 150 to 250, to leave plenty of room for growth
      of common.xml 

      If you prototype a message here, then you should consider if it
      is general enough to move into common.xml later
    -->
     <messages>
          <message id="150" name="SENSOR_OFFSETS">
               <description>Offsets and calibrations values for hardware
        sensors. This makes it easier to debug the calibration process.</description>
               <field type="int16_t" name="mag_ofs_x">magnetometer X offset</field>
               <field type="int16_t" name="mag_ofs_y">magnetometer Y offset</field>
               <field type="int16_t" name="mag_ofs_z">magnetometer Z offset</field>
               <field type="float" name="mag_declination">magnetic declination (radians)</field>
               <field type="int32_t" name="raw_press">raw pressure from barometer</field>
               <field type="int32_t" name="raw_temp">raw temperature from barometer</field>
               <field type="float" name="gyro_cal_x">gyro X calibration</field>
               <field type="float" name="gyro_cal_y">gyro Y calibration</field>
               <field type="float" name="gyro_cal_z">gyro Z calibration</field>
               <field type="float" name="accel_cal_x">accel X calibration</field>
               <field type="float" name="accel_cal_y">accel Y calibration</field>
               <field type="float" name="accel_cal_z">accel Z calibration</field>
          </message>
          <message id="151" name="SET_MAG_OFFSETS">
               <description>set the magnetometer offsets</description>
               <field type="uint8_t" name="target_system">System ID</field>
               <field type="uint8_t" name="target_component">Component ID</field>
               <field type="int16_t" name="mag_ofs_x">magnetometer X offset</field>
               <field type="int16_t" name="mag_ofs_y">magnetometer Y offset</field>
               <field type="int16_t" name="mag_ofs_z">magnetometer Z offset</field>
          </message>
     </messages>
</mavlink>