Which information blocks should not be used in the application of radar or non-radar separation?

The correct answer is that data blocks showing CST or FRZN should not be used in the application of radar or non-radar separation. CST, which typically refers to a 'conflict situation' and FRZN indicating 'frozen' status when an aircraft is temporarily not maneuvering, represent conditions that can mislead controllers. These types of data blocks indicate scenarios that may compromise the integrity of separation assurance, as they do not provide accurate situational awareness for ensuring safe distances between aircraft.

In contrast, data blocks showing relative altitude are relevant for understanding the vertical separation of aircraft, particularly in crowded airspace. Additionally, data blocks from prior flights may contain historical data that can be useful for context or reference but should be verified with current information for real-time decisions. Traffic advisories are critical for alerting controllers to nearby aircraft, allowing them to maintain situational awareness and take corrective actions as necessary. Hence, CST and FRZN data blocks are not suitable when making real-time separation applications.