There are the valid shortcut keys/combinations:

Shortcut keys that don't need modifiers (Shift, Ctrl, or Alt):

"Insert","Delete","F1","F2","F3","F4","F5","F6",
"F7","F8","F9","F10","F11","F12","F13","F14","F15","F16",
"F17","F18","F19","F20","F21","F22","F23","F24",
"Up","Down","Left","Right","Home","End","Page Up","Page Down"

With modifiers - any combination of Shift, Ctrl, and Alt as long as either Ctrl or Alt exists:

The above keys plus letters, numbers, numbers and symbols from the number pad, Enter, Space, Backspace and Break.