Wow, the one submission I've made anywhere that hit the front page, and I'm kicking myself for the title. 'Belt' is really their name for the category of machine architecture in the sense of register and stack machines. 'Mill' is the name of their specific architecture/family.

As far as the meat goes, I'm gratified that I'm not the only one to think this is mindbogglingly elegant. I see some misconceptions in this thread, but I'm finding it difficult to explain the divergences without beginning to inexpertly regurgitate large portions of this and the previous talk (on their instruction encoding).