Edges Section

The first line contains m, the number of edges in the graph. The edges of the graph are ordered by two criteria: first according to the number of their source node and second according to their position in the adjacency list of the source node. Each of the next m lines contains the description of an edge which consists of four space-separated parts:

(a) the number of the source node

(b) the number of the target node

(c) the number of the reversal edge or 0, if no such edge is set

(d) the information associated with the edge (cf. nodes section)

Note: For the data type planar_map the order of the edges is important, because the ordering of the edges in the adjacency list of a node corresponds to the counter-clockwise ordering of these edges around the node in the planar embedding. And the information about reversal edges is also vital for this data type.