The selection looks to me to be an emphasis on readable, English technical typesetting... and then a collection of experiments used to think about features they didn't want to leave out.

Ligatures in Baskerville, mathematical typesetting, box drawing... the layout specs for Tengwar, with its alternate forms and ligatures.

I can't read Hebrew, so I have no idea how usable its implementation is here, but Hebrew was plausibly the most widely used right-to-left text system in North America at the time of publication.

Blows my mind they were doing this in 1976.