IS to select slice from 3D DMDA vector : 
IS Object: 4 MPI processes
  type: general
[0] Number of indices in set 4
[0] 0 2
[0] 1 6
[0] 2 10
[0] 3 14
[1] Number of indices in set 4
[1] 0 18
[1] 1 22
[1] 2 26
[1] 3 30
[2] Number of indices in set 4
[2] 0 34
[2] 1 38
[2] 2 42
[2] 3 46
[3] Number of indices in set 4
[3] 0 50
[3] 1 54
[3] 2 58
[3] 3 62

 Extracted slice vector, in DMDA ordering : 
Vec Object: 4 MPI processes
  type: mpi
Process [0]
0.
0.
100.
100.
Process [1]
0.
0.
100.
100.
Process [2]
200.
200.
300.
300.
Process [3]
200.
200.
300.
300.

 Extracted slice vector, in natural ordering : 
Vec Object: 4 MPI processes
  type: mpi
Process [0]
0.
0.
0.
0.
Process [1]
100.
100.
100.
100.
Process [2]
200.
200.
200.
200.
Process [3]
300.
300.
300.
300.