@Override
	public PSystemXearth executeLine(PSystemXearth system, String line) {
		if (system == null && line.startsWith("xearth")) {
			extractDimension(line);
			system = new PSystemXearth(width, height, config, markers);
			return system;
		}
		if (system == null) {
			return null;
		}
		if (line.startsWith("#") || line.startsWith("'")) {
			return system;
		}
		final Pattern p = MyPattern.cmpile("(\\w+)[%s]*=[%s]*(.*)");
		final Matcher m = p.matcher(line);
		if (m.find()) {
			config.put(m.group(1), m.group(2));
			return system;
		}
		try {
			final Marker marker = Marker.loadMarkerFile(line);
			if (marker != null) {
				markers.add(marker);
				return system;
			}
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
		return null;
	}