I did read, but so ingrained is calling the "controller" MFM, that I literally thought it was referencing the standard, which I think was ST-506 (this was in 1983, so the timing seems to be right?).

EG, I literally thought of the controller and encoding as differing things, both separately called MFM. Ah well, it only took 40 years to discover differently.

Thanks for the link.