how to press F1

[cckp]

a-z is not special key, can be used as is in cmd
as, so need not define

prompt -k a

this works

but you cannot use this:

prompt -k f1


I tried my best to find the keycode for F1
but failed.

i tried ( 14, '~' ) , since F5 is ( 15, '~' ) , but failed

these keys must be something special, there should be some reason. or the programmer just forgot it?