Question: What is the format of the Network Access Identifier (NAI) for a SUCI containing a GLI, as specified in IETF RFC 7542?
Option 1: username#realm
Option 2: realm@username
Option 3: username@realm
Option 4: realm.username
Explanation: The NAI format for a SUCI containing a GLI is specified to be in the form of "username@realm", where the realm part is identical to the realm part of the SUPI, and the username part is encoded as specified for the null-scheme. This ensures that the NAI can be used to identify the user and the network they are accessing.