Hi, while working on the ShapeMergeFilter I found this because I wanted to add a field for the OSM id: MapShape extends MapLine which extends MapElement. I wonder if that makes sense as MapElement contains 8 fields which are not usable with shapes: private String zip,country,region,city,street,phone,houseNumber,isIn; Esp. with small shapes like small buildings these fields are quite a big memory overhead. Doesn't Java offer a better solution for this case? Gerd