Attractor basin are represented by state transition graphs, where nodes representing network states are linked by directed arcs representing state transitions. Attractor basin topology consists of transient trees rooted on attractor cycles. The attractor cycle may have an arbitrary period, including a period of just one, a point attractor cycling to itself. Transient trees may consist of just one node outside the attractor, or a number of nodes with arbitrary in-degree (but one out degree) at each node. Nodes with zero in-degree, the leaves of the trees, are the so called garden-of-Eden states. The graphic conventions for drawing attractor basins and subtrees are described below.