I imagine it would be rectangular timber plate laid flat on top of stud wall, bolted double timber trimmer beam along the wall face (if spanning unsupported). Rafters notched onto timbers at both ends with birdmouth joints (2/3 depth of rafter typically) and frame cramps/rafter cramps/
truss clips to hold things in place. NB to nog the rafters to brace them and stop rotation. Rafters and roofing should oversail the walls to give rain protection. SFAIK roof finishes should lap over eaves board and membrane brought back under. (Think about where drips form/runoff goes).