Reference points

                0     A D G B E
                    -----------                  
                    | | | | | |
                    -----------
                    | | | | | |
                    -----------
                    | | | | | |
                    -----------
                    | | | B | |
                    -----------
                5   A D G | E |
                    -----------
                    | | | | | |
                    -----------
                    | | | | | |
                    -----------
                    | | | | | |
                    -----------
                    | | | | | |
                    -----------
                    | | | | | |
                    -----------
                    | | | | | |
                    -----------
                12  | A D G B E
                    -----------
                    | | | | | |