Preferences projectNode = node.node(projectId);
for( String mapId : projectNode.childrenNames() ) {
URI mapURI = URI.createURI(URI.decode(mapId));
Preferences mapNode = projectNode.node(mapId);
String mapName = mapNode.get(KEY_NAME, null);
for( String bmarkName : mapNode.childrenNames() ) {
Preferences bmarkNode = mapNode.node(bmarkName);
double minx = bmarkNode.getDouble(KEY_MINX, 0.0);
double miny = bmarkNode.getDouble(KEY_MINY, 0.0);
double maxx = bmarkNode.getDouble(KEY_MAXX, 0.0);
double maxy = bmarkNode.getDouble(KEY_MAXY, 0.0);