Following on from my recent diagram of the OWL-Time ontology, here's one depicting some of the properties defined in the ontology and how they relate to instants and intervals:

I don't think it's as clear as the previous one so here's the key: t1, t2 and t3 are instants in time, P1, P2, P3, P4 are proper intervals. The blue arrows represent properties, the tails are attached to the subjects of the properties and the heads to the values. Read the first arrow at the top as the triple _:t1 :before _:t2 .

By the way both these images (1 and 2) are in the public domain so if you find them useful please take them.