Hierarchical Layout - Flow Direction Parameter
Flow Direction
The flow direction parameter specifies the direction
in which the majority of the links should point. If the flow direction is
to the top or to the bottom, the node levels are oriented horizontally and
the links mostly vertically. If the flow direction is to the left or to the
right, the node levels are oriented vertically and the links mostly horizontally.
If the flow direction is to the bottom, the nodes
of the level with index 0 are placed at the top border of the drawing. The
nodes with level index 0 are usually the root nodes of the drawing (that
is, the nodes without incoming links). If the flow direction is to the top,
the nodes with level index 0 are placed at the bottom border of the drawing.
If the flow direction is to the right, the nodes are placed at the left border
of the drawing.

Figure 1 - Flow Directions