Question: What format does the User-Name AVP (AVP code 1) contain the user name in, according to the referenced standard?
Option 1: UTF-8 encoded hexadecimal string
Option 2: NAI (Network Access Identifier) format as per RFC 6733
Option 3: IETF RFC 4006 defined ABNF grammar
Option 4: TS 23.003 specified IMEISV composition
Explanation: The correct answer is Option 2 because the User-Name AVP (AVP code 1) contains the user name in the format of a Network Access Identifier (NAI) as defined by RFC 6733, ensuring standardized formatting for user identification in telecommunication networks.