It's likely some arbitrary jargon that someone made up. I have my own method of reading, which since we're throwing out pretentious flowery prose, I'm going to call "predictive perusal".
For each chapter or titled section, I read the first sentence or title and then mentally position myself as the writer of that section and attempt to predict the contents. For convergence I attempt to traverse further plies. For divergence, I attempt to figure out the root of the difference.
EDIT: For the record, I have never felt the need to scribble in the margins of a book. It's far better to take notes on separate media to prevent "preloading" your existing thoughts at the time should you choose to re-read the book years later.
