Further clarification:
"Face buttons" are the shapes: triangle, square, X and circle.
"Shoulder buttons" are L1, L2, R1 and R2.
L3 and R3 are the "clickers" -- press the top of the sticks into the controller.
Hope this helps someone... I know a guy who almost lost his mind, I let him borrow my copy of GTA3 (way back when) and he was just getting *really into* the game and the mission required a horn honk with R3. He could not find the R3 clicker. When I got home from work and he came running over, I thought he was going to attack me or his head would explode or something. LOL. I explained that his PS2 owner manual shows him all the button locations on the controller. Yes I was a smartass and he did not like that.