This feature is needed to analyse how cell's value is produced by formula. Dependency Auditor will divide formula into sub-expressions and evaluate each one. You will see value of each expression and it's parts recursively.
For example, we have the following formula A4=A3+A2+A1+1. On the first step
we'll see following expressions:
After expanding A3+A2+A1 node:
You can expand all nodes recursively, to see evaluation of other cells(arguments) and expressions.