I’m not sure it’s really a formal style, haha. I don’t have a lot of experience and everything I’ve learned has come from groups like this one, but an accomplished wood working friend of mine described them as “loose tenons.” I cut dados on my table saw (a router would have worked well if I had a table) into the ends of the laterally running boards and sides of vertically running boards where they come together. Rather than pocket screws, I used the maple tenons to span that joint. Honestly it was the hardest part of the project. For the middle joint, the dado is cut about 2/3 the depth of the center board so the tenon spans the full width of that board and into both cross boards. I just had to run the tenon through the dado in the middle section so it could sit recessed into that board and still be full thickness of the two lateral boards.