Enabling Engineering Mode in xDrip+ activates extended and experimental features within the app.
To enable Engineering Mode, on the xDrip+ home screen tap the Treatment icon on the right side of the screen (this resembles a syringe). Then tap and hold the microphone icon on the bottom-right of the Treatment interface. In the text field that opens, type "enable engineering mode" and click Done. Or, when Google Speak engine is active, speak the command "enable engineering mode". Engineering Mode is now enabled.