Each component or test point can have one of 6 statuses.
Good (green)
A good test or component is obviously working with the specified parameters. I.e. the voltage is 12V +- 1V, or the mechanical adjustment is within 5 +- 1mm, etc.
Bad (red)
The component or test is not operating within the specified parameters or is physically broken. Repairing it could mean a total replacement or at least a calibration to bring it back into the specified range.
Suspect (yellow)
The component's status is unknown, but it could be contributing to the currently selected error or symptom.
Indeterminate (blue)
The component is downstream of a bad component or test point, therefor its status cannot be determined, as its input is bad.
Off path (blue)
This component has nothing to do with the currently selected symptom or fault. For example, the air-conditioner in the operator's cabin has no influence on the hoist brake function.