Such nanopublications expresse a causal (e.g. "A caused B"), spatio-temporal (e.g. "A is included in B"), or comparative (e.g. "A is larger than B") relation between two things.

Note that the left-hand side element (subject) as well as the right-hand side one (object) need to be individuals that exist just once, like the French revolution or the Internet, and not classes that stand for an entire collection of things, like city or headache.