Managing Lightroom Presets in Lightroom Classic 7.3 or later

Ever since adobe updated Lightroom earlier this moth and changed the way presets are stored, there has been a lot of confusion around the new system, and I myself have been caught out by this too. In fact, I was so confused by the changes, I mistook one aspect of the new format completely wrong, and ended up putting out some incorrect information. Luckily a reader set me straight, and so here is the semi definitive guide to the new preset format.