What does a capital A (without an underscore) do in AutoHotKey?
For example, the following script (taken from here) changes the current language to Russian, and it uses a capital A:
ru := DllCall("LoadKeyboardLayout", "Str", "00000419", "Int", 1)
PostMessage 0x50, 0, %ru%,, A
P.S. all A_ variables are listed here, but A isn't.