Polygon in kicad

[KiCADsmktec]

I am creating a program that translates the pcb from kica_pcb in a CAD software including tracks, vias etc.
Now I found in the file kicad_pcb a part like

(zone (net 1) (net_name GND) (layer B.Cu) (tstamp 5CC7D701) (hatch edge 0.508)
(connect_pads (clearance 0.508))
(min_thickness 0.254)
(fill yes (arc_segments 16) (thermal_gap 0.508) (thermal_bridge_width 0.508))
(polygon
(pts
(xy 42.545 49.53) (xy 91.44 49.53) (xy 91.44 98.425) (xy 42.545 98.425)
)
)
(filled_polygon
(pts
(xy 91.313 98.298) (xy 42.672 98.298) (xy 42.672 94.304) (xy 60.78256 94.304) (xy 60.78256 96.704)
(xy 60.831843 96.951765) (xy 60.972191 97.161809) (xy 61.182235 97.302157) (xy 61.43 97.35144) (xy 63.03 97.35144)…
which obviously describes Cu-areas which are connected to ground. I have downloaded the latest file_formats.pdf file. But the description of polygons in there appears to me very different to what I find in kicad_pcb. I need points or lines that describe a closed polygon.
Could anybody help, please

[Seth_h]

The (polygon) tag is the outline without filled copper. the (filled_polygon) tag is the copper itself. If you are manufacturing the pcb, you care about filled_polygon, if you are translating to edit the file, you care about polygon