Question: What mechanism ensures forwards and backwards compatibility in UTRAN Iu interface RANAP signalling for current and future messages, Information Elements (IEs), or groups of related IEs?
Option 1: Inclusion of ID and criticality fields in a standard, unchanging format within each message or IE.
Option 2: Periodic revision of the protocol to incorporate backwards compatibility with previous versions.
Option 3: Mandatory use of optional IEs for future-proofing.
Option 4: Implementation of a version indicator at the beginning of each signal.
Explanation: The correct answer highlights the specific technical mechanism (inclusion of ID and criticality fields in a standard format) that ensures both forwards and backwards compatibility, allowing for seamless decoding of messages across different standard versions, crucial for maintaining interoperability as the protocol evolves.