Section 59 Not forwards
This metric merely shows whether an arrow in the causal map does not point forwards, i.e. it points backwards or to another variable in the same “column” as it.
Which specific arrow is identified depends on the specifics of the algorithm which calculates the layout (Sugiyama). But the great thing about the metric is it reveals where there are cycles in the network. If you were to delete these arrows, there would be no cycles.
Often, when laid out sensibly, there are fewer loops than people think.