Initial Vec A
Vec Object: 1 MPI process
  type: seq
0.
1.
2.
3.

Broadcast A->B over sfA
Vec Object: 1 MPI process
  type: seq
3.
2.
1.
0.

Broadcast B->BA over sfB
Vec Object: 1 MPI process
  type: seq
3.
2.
1.
0.

Broadcast A->BA over sfBA (sfB o sfA)
Vec Object: 1 MPI process
  type: seq
3.
2.
1.
0.
PetscSF Object: sfA 1 MPI process
  type: basic
  [0] Number of roots=4, leaves=4, remote ranks=1
  [0] 0 <- (0,3)
  [0] 1 <- (0,2)
  [0] 2 <- (0,1)
  [0] 3 <- (0,0)
  MultiSF sort=rank-order
PetscSF Object: sfB 1 MPI process
  type: basic
  [0] Number of roots=4, leaves=4, remote ranks=1
  [0] 0 <- (0,0)
  [0] 1 <- (0,1)
  [0] 2 <- (0,2)
  [0] 3 <- (0,3)
  MultiSF sort=rank-order
PetscSF Object: (sfB o sfA) 1 MPI process
  type: basic
  [0] Number of roots=4, leaves=4, remote ranks=1
  [0] 0 <- (0,3)
  [0] 1 <- (0,2)
  [0] 2 <- (0,1)
  [0] 3 <- (0,0)
  MultiSF sort=rank-order