<para>
Because the format supports only one route, this option may be used 
on output to select a single route from a collection of 
routes read from a more expressive format.  If you have, say, a 
<link linkend="fmt_gpx">gpx</link> file that contains two routes, you may
use this option to write them one at a time to individual files.
</para>
<para><userinput>gpsbabel -i gpx -f routes.gpx -o nmn4,index=1 -F route1.rte -o nmn4,index=2 -F route2.rte</userinput></para>

