The UC3-A3 Xplained has four yellow LEDs which are connected to the AT32UC3A3256 and all of them are active low.
One dual LED is mounted near the USB connector. It has one green LED which is used to indicate power and one red LED that can be used for other purposes. The green LED will be active when power is applied to the board but it can be disabled by software from the AT32UC3A3256 device if needed. The red LED is active low and the green LED is active high.