The values in the direction code show the direction of the 
adjacent downstream grid cell.

This 3x3 kernel indicates the direction of connectivity
for the each grid cell:

 32  64 128
 16   0   1
  8   4   2

A value of 16 indicates the grid cell is connected to, and 
draining downstream to, the cell to its immediate left.  A 
value of 2 means the cell drains to the lower right adjacent 
cell.  A value of 0 means the cell does not drain to an adjacent
grid cell.  The NoData value = -9999.