Back edges are drawn in the opposite direction as compared to ordinary edges. For instance, if the layout algorithm tries to give all ordinary edges a top-down orientation, it tries to give the back edges a bottom-up orientation.
If a graph contains a cycle, not all edges can have the same orientation: Some edges have to be reversed. In this case, the layout algorithm prefers back edges before selecting any other edge to be reversed.
A back edge is specified by
backedge: {
sourcename:
< title of source node >
targetname:
< title of target node >
< list of edge attributes >
}