Thanks.

I was clear from the documentation (and from stackoverflow, etc.) that graphml was the format I needed.  However, Graph.save doesn't mention graphml.  I see now that there is enough information on those two pages to deduce that graphml== xml (that is, both pages mention "dot" and "gml" and so one might be able to assume that the third terms, which are different in each, are meant to be the same).   However, I think it would be helpful to clarify that in the Graph.save docstring.

For example, change the doc string to:

Save graph to ``file_name`` (which can be either a string or a
        file-like object). The format is guessed from the ``file_name``, or can
        be specified by ``fmt``, which can be either "xml", "dot" or "gml".
        Only "xml", also called graphml, preserves all information in the graph.

Graph.load might be changed similarly.

But if you don't get many people on the list confused about it, maybe it isn't worth it.  Just my 2 cents.  Thanks again for the great package and your hard work!

-Elliot