<para>Specifies a backup file for the binary logger data. New waypoints from the logger will be appended to an existing 
backup file. This allows you to create "endless" binary logger files which, for example, could contain the waypoint data of a whole year.</para>
<para>The backup file can be read with gpsbabel by  using the itracku format.</para>

<example id="itracku-backup">
  <title>Download from the data logger while and append the new binary logger data to a backup file. Read the contents of the backup file.</title>
  <para><userinput>gpsbabel -i itracku,auto,backup=itracku.bak -f dummy -o gpx -F out.gpx</userinput></para>
  <para><userinput>gpsbabel -i itracku -f itracku.bak -o gpx -F out.gpx</userinput></para>
</example>

