In non-functional testing of a safety-critical monitoring system, which aspect would least likely be addressed in the test plan?

In the context of non-functional testing for a safety-critical monitoring system, the primary concerns typically include aspects directly related to the system's performance, safety, and operational stability. Availability, safety, and reliability are critical parameters that ensure the system can perform its functions effectively and safely in real-world scenarios.

Portability, on the other hand, refers to the ease with which the system can be transferred from one environment to another, such as from one platform or operating system to another. While portability might still hold value in certain contexts, it is generally less relevant in safety-critical systems where the primary focus is on ensuring consistent and safe operation rather than the ability to move or adapt the system easily.

Thus, in a test plan focused on non-functional testing for a safety-critical monitoring system, portability would be the aspect that is least likely to be prioritized, since the fundamental aim is to ascertain that the system meets stringent reliability, availability, and safety standards rather than testing how easily it can migrate across different environments.