Block 25 on a flight strip specifies which of the following?

Block 25 on a flight strip is designated for the route of flight, which includes critical information about the aircraft's planned journey from its point of origin to its intended destination. This section provides air traffic controllers with a concise view of the flight path, ensuring they can adequately manage air traffic and maintain safety and efficiency in the airspace.

The inclusion of the route details allows controllers to understand how the flight will integrate with existing traffic and enables them to provide the necessary instructions for any changes that may be required during the flight. Understanding the route of flight is essential for ATC in managing sector loads and predicting potential issues, thereby maintaining a safe operating environment.

While the other options refer to important flight information, they are addressed in different sections of the flight strip and do not pertain to Block 25 specifically.