An article I ran acrosss a few days back pointed out how the nature relationships also matters. It starts off noting that gender is often given as binary (M/F), when reality can be more complicated (though most of the complications are a distinct minority case). That's something I ran across years back looking at healthcare data, where "gender" had in some cases five values: male, female, indeterminate, other, and unknown.

Relationships, though: "friend", "family", "co-worker", "ex-spouse", "enemy", ...

Any thoughts on capturing something such as this (or of similar complexity) on a graph? Or references?

I suspect international or inter-corporate relationships might be similar.