How are FD codes displayed?

FD codes, or flight data codes, represent formatted flight plan information that is used in the context of aviation data communication. The correct format for displaying FD codes is represented by the structure "ddff +/- tt."

In this format, "dd" typically stands for the departure point, "ff" represents the flight number or some form of identification, and "tt" reflects the type of code or status. The use of "+" or "-" indicates whether the information is an addition to or a subtraction from the standard data presented. This structured format ensures clarity and uniformity in the communication of flight data, allowing pilots, air traffic controllers, and monitoring systems to efficiently interpret and respond to flight information.

Other formats presented in the choices do not align with the established standards of FD code displays, making them less appropriate for effective data representation in aviation.