Y, U, I, O, P and Delete are the F keys, if you press it with function. Y is F1, U is F2, I is F3, O is F7, P is F8, Delete is F9. If you press shift and function, Y=F4, U=F5, I=F6, O=F10, P=F11, Delete is F12.
The way it kinda jumps around, to where one key will be right next to one that has a value of several higher.