#+name: block_data_missing
| 1 | 1 |  2 |
| 1 | 2 |  5 |
| 1 | 3 | 10 |
|   |   |    |
| 2 | 1 |  5 |
| 2 | 2 | 10 |
| 2 | 3 | 13 |
|   |   |    |
| 3 | 1 | 10 |
| 3 | 2 |  ? |
| 3 | 3 | 18 |
|   |   |    |
|   |   |    |
| 1 | 1 | 12 |
| 1 | 2 | 15 |
| 1 | 3 | 20 |
|   |   |    |
| 2 | 1 | 15 |
| 2 | 2 | 18 |
| 2 | 3 | 23 |
|   |   |    |
| 3 | 1 |  ? |
| 3 | 2 | 23 |
| 3 | 3 | 28 |

#+name: gnuplot_3
#+begin_src gnuplot :var d=block_data_missing
  set ticslevel 0
  splot d index 0 u 1:2:3 w lp pt 6 ps 5, d index 1 u 1:2:3 w lp pt 6 ps 5
#+end_src