What term refers to a unique identifier that is not modified when requirements are altered?

The term that refers to a unique identifier that remains unchanged even when requirements undergo modification is known as a Unique Identifier. This identifier is critical in the requirements management process because it allows stakeholders to consistently refer to specific requirements without confusion, regardless of any changes that occur later.

Unique Identifiers ensure that all discussions, documentation, and traceability matrices maintain a clear reference point. They are assigned to requirements when they are created and do not change despite alterations, preserving the history of changes and the context around each requirement. This constancy is essential for effective communication and management of requirements throughout the project lifecycle, as it helps teams maintain alignment and clarity, even as requirements evolve.

Other terms mentioned might reflect aspects of tracking or referencing requirements, but they do not encapsulate the idea of an unchanging reference point in the same way a Unique Identifier does.