<para>
This format is used by GPSBabel itself as the input to the 
<link linkend="filter_arc">arc</link> and 
<link linkend="filter_polygon">polygon</link> filters.  See those filters
for more information.
</para>
<para>
The arc format reads two numeric fields, a latitude and a longitude, 
in any format recognized as <link linkend="style_def_lathuman">human 
readable</link> and writes as simple degrees decimal.  It really is
intended for GPSBabel's own internal use more than general use, though
it turns out to be a convenient way of expressing simple polylines and 
polygons.
</para>
