When using a certified aircraft navigation system for RNAV and RNP operations, what restrictions must be adhered to?

In the context of RNAV (Area Navigation) and RNP (Required Navigation Performance) operations using a certified aircraft navigation system, adherence to specific restrictions is vital for safe and effective navigation. Selecting the option that includes all necessary considerations captures the full scope of compliance required.

Using official waypoints is essential to ensure pilots are following pre-approved routes that have been validated for safety and operational efficiency. Modifying database waypoints could lead to incorrect navigation and is typically not permitted unless under special circumstances and in accordance with strict operational guidelines. Adhering to maximum altitude specifications outlined in the technical orders (T.O.) guarantees safe vertical separation from terrain and obstacles, as well as from other air traffic. Together, these aspects ensure that the aircraft navigation system operates within required parameters for safety and accuracy.

Thus, the recognition that all these factors play a critical role makes the answer that includes them all the most appropriate choice for understanding the restrictions when utilizing certified aircraft navigation systems for RNAV and RNP operations.