Sticky Modifier Keys
When entering a symbol or using a shortcut requires a key combination, the Sticky Keys feature lets the user press a modifier key, such as Shift or Fn and have it remain active until another key is pressed. This eliminates the need for pressing multiple keys simultaneously on such a small keyboard.
If for example, the user types a, shift, b, c the driver should send aBc. If the user types a, shift+b, c the driver should send aBc.
Note that not all devices support modifier keys, especially devices with 9–key keyboards.