Eclipse plug-ins are Existions?

Is that even a word? Ivar Jacobson seems to think so, and that's good enough for me. I just received my latest purchase from Amazon, titled "Aspect-oriented Software Development with Use Cases" by Ivar Jacobson and Pan-Wei Ng, and to my surprise, on page 13 is a diagram of the Eclipse architecture! In short, an Existion has extension points, into which extensions contribute. What's even more surprising is that this is from a 1986 paper Language Support for Changeable Large Real-Time Systems (OOPSLA '86, pp.377-384), which in turn explores ideas of a 1981 patent application!!! (Which was denied because it looked too much like an already patented - get this - patching technique :-). Wow...