^         t                                                                   
  |         t                                                                   
  |   t  t  t                                                  t           t    
  |   t  t  t     t                                         t  t     t  t  t    
  |   t  t  t  t  t  t        t                          t  t  t  t  t  t  t    
  |   t  t  t  t  t  t  t  t  t                       t  t  t  t  t  t  t  t    
  |   t  t  t  t  t  t  t  t  t                       t  t  t  t  t  t  t  t    
  |   t  t  t  t  t  t  t  t  t rt                    t  t  t  t  t  t  t  t    
  |   t  t  t  t  t  t  t  t  t rt              t r   t  t  t  t  t  t  t  t    
  |   t  t  t rt rt  t rt rt rt rt  t  t  t rt  t rt  t  t  t  t  t rt  t  t    
 -+---------------------------------------------------------------------------> 
  |  15 16 17 18 19 20 21 22 23 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14