Cabinet "Applied Back"

I’m reading Gregory Paolini’s “Kitchen Cabinets Made Simple”. His construction technique for these cabinets is butt joints with steel screws (Please, let’s not debate butt joints here). For upper cabinets, there is a 1/4” back that is in front of 3/4” nailers. The sides are screwed to the 3/4” nailers, and then the entire cabnet is attached to the wall with screws.

Ok, then he makes the statement “If you plan to store heavy items in your wall cabinets, consider using an applied back for added strength.” He defines the applied back as just a solid piece of 3/4” ply instead of the nailers + 1/4” piece.

This is the page in question if you want to read it.

However – is the 3/4” applied back attached to the back of the side pieces (in other words, screwed to the sides from the very back of the back piece OR is it just a solid 3/4” piece placed in between the two side pieces and screwed in from the sides? It’s not clear to me and this statement doesn’t help: “When cutting components, reduce the depths of the sides, top and bottom by roughly 3/4” to accommodate the applied back….Eliminate the nailer strips and the 1/4” back from your cut list because the applied back takes the place of these components.” The last 2 sentences seem at odds with each other.

Anyone know?
Cheers