Finally! We see a modern presentation of the topics addressed by turing in his unpublished manuscript on permutations. Perhaps the editor, noting the missing title, should have called it on mixing.
Looking at the very specific gccs terminology turing uses, and given the extra context that this stanford professor adds concerning the design of rotor wiring schemes (and pseudo wiring, by extension, in the spn of the des) based on expander graphs ideas, we can see what both were/are not allowed to say openly … concerning cryptographic design method, per se.
Its nice to see this prof use non pretentious language.