private float AssignDL(XmlNode n1, XmlNode n2)
	{
		if (n1 == null && n2 == null)
			throw new RuntimeException("Xml node n1 and n2 could not be null");
		
		Coordinate c1 = this.tree.getCoordinate(n1);
		Coordinate c2 = this.tree.getCoordinate(n2);
		
		if (c1 == null && c2 == null)
			throw new RuntimeException("c1 and c2 can not be null");
		
		return (float)c1.distance(c2) / 300000000 * 1000;
	}