Section: 28.7.8 NAI format for 5G-GUTI
Content: The NAI format of the 5G-GUTI shall have the form username@realm as specified in clause 2.2 of IETF RFC 7542 [126]. The username part of the NAI shall take the following form: tmsi<5G-TMSI>.pt<AMF Pointer>.set<AMF Set Id>.region<AMF Region Id> <5G-TMSI>, <AMF Pointer>, <AMF Set Id> and <AMF Region Id> are the hexadecimal strings of the 5G-TMSI, AMF Pointer, AMF Set ID and AMF Region ID. If there are less than 8 significant digits in <5G-TMSI>, "0" digit(s) shall be inserted at the left side to fill the 8 digits coding. If there are less than 2 significant digits in <AMF Pointer> or <AMF Region Id>, "0" digit(s) shall be inserted at the left side to fill the 2 digits coding of the AMF Pointer or AMF Region Id respectively. If there are less than 3 significant digits in <AMF Set Id>, "0" digit(s) shall be inserted at the left side to fill the 3 digits coding. Example: Assuming 5G-TMSI = 06666666 (hexadecimal), AMF Pointer=12 (hexadecimal), AMF Set = 001 (hexadecimal), AMF Region = 48 (hexadecimal), the username part of the NAI is encoded as: "tmsi06666666.pt12.set001.region48" The NAI for an N5CW device in a PLMN (either HPLMN or VPLMN) with MNC=012 and MCC=345, to which the N5CW device attempts to connect via the trusted non-3GPP access, according to clause 28.7.7 is: "tmsi06666666.pt12.set001.region48@nai.5gc-nn.mnc012.mcc345.3gppnetwork.org"