@Carl Love 

(Thanks very much)

with(GraphTheory):with(LinearAlgebra):
A:=Matrix([[0,2,3],[4,0,5],[6,7,0]]);
G:=Graph(A);
Export("ExampleOfWeightedDigraph.graphml",G);
G2:=Import("ExampleOfWeightedDigraph.graphml");
WeightMatrix(G),WeightMatrix(G2);