`EJCT` keycode works on OSX. https://github.com/tmk/tmk_keyboard/issues/250
+It seems Windows 10 ignores the code and Linux/Xorg recognizes but has no mapping by default.
Not sure what keycode Eject is on genuine Apple keyboard actually. HHKB uses `F20` for Eject key(`Fn+f`) on Mac mode but this is not same as Apple Eject keycode probably.
tmk