The Yaesu FT-817ND transceiver has four different transmitter output power levels: 5 W, 2.5 W, 1 W and 0.5 W. However, the visual indicators can be confusing as the differ slightly depending on whether the radio is powered via its external connector with a voltage exceeding 11.5 V or if the radio is running on its own internal battery (or the external voltage is less than 11.5 V). This nifty info-graphic should remove all remaining ambiguities:

Excellent !
Clear and concise.
It helped me a lot.
Thank you.