I have produced a polygon filter file, for the area of Germany -
Germany.txt, as described in Chapter 4. of the GPSBabel PDF manual. I
used a map of Germany displayed in OziExplorer and manually produced a
file Germany.plt. I then edited it quickly in Excel.
It worked to filter waypoints/POIs of Europe into just those in
Germany. It took a long time to produce the .plt file.
Does anyone know if files are available for other European countries?