The colour of the Tecla Shield's status light indicates the current mode.
Switch Control (white)
This mode works in combination with Apple's Switch Control accessibility feature (available on iOS7 and above). With this mode, you can assign each switch connected to the Tecla Shield to a specific action, such as "Select Item". Download Manual
App Control (blue)
This mode can be used with "switch accessible" iOS apps that use Space and Enter as switch inputs. Download Manual
iOS Classic (purple)
This mode uses Apple's VoiceOver facility. It allows for linear scanning navigation (i.e., next/previous item) and works in all iOS versions. Download Manual