<para>
When this option is specified, only points that are within the specified 
distance of one of the vertices of the arc are kept.  This differs from the
normal mode of operation in that in the normal mode, points that are close to
the lines between points are also kept.
</para>
<para>
This option makes the arc filter act like a multi-point version of the
<link linkend="filter_radius">radius</link> filter.
</para>

