<para>
This option computes (or recomputes) a value for the GPS heading at each 
trackpoint.  This is most useful with trackpoints from formats that don't 
support heading information or for trackpoints synthesized by the 
<link linkend="filter_interpolate">interpolate</link>
filter.  The heading at each trackpoint is simply the course from the
previous trackpoint in the track.  The first trackpoint in each track
is arbitrarily assigned a heading of 0 degrees.
</para>

