Right at the beginning with this idea of composition by field. Which is where I assume Prynne gets his notion of poem as diagram. He talks about Pound's poetry in his way, and presumably his own too. So rather than a moving through time you have a drawing of a machine and the relationships of force and acting upon and so on. I can track down the relevant passage if anyone is curious. But I think it is an intriguing distinction. I really like it.