<-- L1 <-- L2 <-- DS1
P1                    |
   <--------- L3 <----|

--------------------------------------
|project Ver|  L1  |  L2  |  L3  | DS1 |
|--------------------------------------|
|   A       |  1.0 |  1.1 |  1.3 | 1   |
|   B       |  1.2 |  1.2 |  1.4 | 1   |
|   C       |  1.4 |  1.3 |  1.5 | 1   |
|   D       |  1.5 |  1.5 |  2.8 | 2   |
                   .
                   .
                   .