When the C-3 exterior door light is amber, what does it indicate?

The indication of an amber C-3 exterior door light signifies that the door is disabled. This means that the door is in a state where it cannot be operated due to safety or operational restrictions. The amber light serves as a warning to crew members and maintenance personnel that the door is not usable at that moment, ensuring that safety protocols are followed and preventing unintended door operations. Understanding the meaning behind these indicator lights is critical for safe train operation and effective communication among crew members.