Are the ParMetis programs valid for directed graph partition?

Hello everyone,I have seen that the ParMetis is not valid for directed graph partition unless convert it into undirected graph in this forum,but after I deleting some edges of a undirected graph at some lines(the rotor.graph in Parmetis Graph),it also can run correctly.How to explain it? It may means directed graph also can run in the ParMetis programs.Is it right?