Example of a rooted split system depicted as a split network and a table of splits. Each split has been assigned a number and is represented by one or more parallel edges in the split network (e.g., the two lines labeled 10 represent the split A₁A₂|B₁B₂C₁O₁O₂). The split system contains taxa from three communities labeled A, B, and C and has been rooted using the outgroup taxa labeled O. Splits are classified with respect to communities A and B: unique to community A (U_A: purple), unique to community B (U_B: purple), shared (S: green), root (R: orange), external (E: gray), or outgroup (O: blue).