It is the typical network used in a branching context, as in deployment and aggregation models. We will modify it further here, for this kind of process. Connections To describe a branching system where we are concerned about reaching destinations, we start with a relatively simple set of descriptions, and add to them as necessary. Nodes Number the nodes in a way that makes sense, but remember that node numbers are labels, and order is unimportant in an absolute sense. This is how we keep track of ordering, without restricting the way that nodes are numbered.
Branches Assume positive down.
This is the typical convention in these models. Unless we deviate from this convention, we don't need to include it in every branch notation. Define branch probabilities or proportions. This is the probability that a branch will be taken, the proportion of times that a branch will be traversed, etc. Define branch quantities as needed.