[MikeE]

The vision targets are very helpful because you have control over their hue by your choice of illumination source. But the vision targets are at each end of the alliance wall, so there might be circumstances when they are not visible to a robot.
There should also be at least a letter I shaped set of lights illuminated towards the center of the alliance goal any time an alliance has the ball during a cycle. While this will be less reliable than the vision targets it might provide an additional indication for added robustness.