Isim and Esim for graph method

Hi. I am trying to reproduce the values of Isim/Esim when using the graph method. My understanding is that these are usually the average similarities computed by the distance measure (in this case Cosine). I get similar values by computing just this when using other methods (direct, rbr), but the results are different when using clmethod=graph.
So I'm guessing in this case the reported values are something else related to the graph algorithm but I can't find it in the manual. Any pointers would be greatly appreciated