Output pathway files in the standard SPRAS format include a header row and rows providing attributes for each edge.
The header row is Node1 Node2 Rank Direction.
Each row lists the two nodes that are connected with an edge, the rank for that edge, and a directionality column to indicate whether the edge is directed or undirected.
The directionality values are either a 'U' for an undirected edge or a 'D' for a directed edge, where the direction is from Node1 to Node2.
Pathways that do not contain ranked edges can output all 1s in the Rank column.
For example:
Node1 Node2 Rank Direction
A B 1 D
B C 1 D
B D 2 U
D A 3 U