What must be included when modifying a filed flight plan for computer acceptance?

When modifying a filed flight plan for computer acceptance, an FRC (Flight Plan Release Center) notation is crucial. This notation serves as an acknowledgment that the changes made to the flight plan have been reviewed and are in accordance with regulatory and procedural requirements. The FRC notation ensures that all necessary modifications are recorded and communicated effectively, facilitating coordination among various air traffic control entities and enhancing safety by ensuring that everyone involved is aware of the updated details of the flight plan.

While elements such as the assigned altitude, pilot's contact information, and compliance checks may be essential in various aspects of flight planning or communication, they do not specifically pertain to the computer acceptance process for modifications. The focus of computer acceptance is on ensuring that the flight plan modification is in compliance with the standardized notation protocols, which is why the FRC notation is the correct answer in this context.