Section: 5.2.2.3.3 ATTEMPTING-REGISTRATION
Content: The UE in 3GPP access: a) shall initiate an initial registration procedure on the expiry of timers T3502, T3511 or T3346; b) may initiate an initial registration procedure for emergency services even if timers T3502, T3511 or T3346 are running; b1) may initiate an initial registration procedure even if timer T3502, T3346 or T3447 is running, if the UE is a UE configured for high priority access in selected PLMN; b2) may initiate an initial registration procedure even if timer T3502, T3346 is running, if the UE is a UE configured for high priority access in selected SNPN; c) shall initiate an initial registration procedure when entering a new PLMN or SNPN, except i) if timer T3346 is running and the new PLMN or SNPN is equivalent to the PLMN or SNPN where the UE started timer T3346; ii) if the PLMN identity of the new cell is in the forbidden PLMN lists; iii) if the SNPN is not an SNPN selected for localized services in SNPN (see 3GPP TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [5]), the SNPN identity of the new cell is in the "permanently forbidden SNPNs" list or the "temporarily forbidden SNPNs" list which are, if the MS supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription; iv) if the SNPN is an SNPN selected for localized services in SNPN (see 3GPP TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [5]), the SNPN identity of the new cell is in the "permanently forbidden SNPNs for access for localized services in SNPN" list or the "temporarily forbidden SNPNs for access for localized services in SNPN" list, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription; or v) if the current TAI is in one of the lists of 5GS forbidden tracking areas; d) shall initiate an initial registration procedure when the current TAI has changed, if timer T3346 is not running, the PLMN identity of the new cell is not in one of the forbidden PLMN lists or the SNPN identity of the new cell is in neither the "permanently forbidden SNPNs" list nor the "temporarily forbidden SNPNs" list which are, if the MS supports access to an SNPN using credentials from a credentials holder, equivalent SNPNs or both, associated with the selected entry of the "list of subscriber data" or the selected PLMN subscription, and the current TAI is not in one of the lists of 5GS forbidden tracking areas; e) shall initiate an initial registration procedure if the 5GS update status is set to 5U2 NOT UPDATED, and timers T3511, T3502 and T3346 are not running; f) may initiate an initial registration procedure for UE in NB-N1 mode upon receiving a request from upper layers to transmit user data related to an exceptional event and the UE is allowed to use exception data reporting (see the ExceptionDataReportingAllowed leaf of the NAS configuration MO in 3GPP TS 24.368[ Non-Access Stratum (NAS) configuration Management Object (MO) ]  [17]) or the USIM file EFNASCONFIG in 3GPP TS 31.102[ Characteristics of the Universal Subscriber Identity Module (USIM) application ]  [22]) if timer T3346 is not already running for "MO exception data" and even if timer T3502 or timer T3511 is running; and g) may initiate an initial registration procedure with 5GS registration type IE set to "initial registration" for initiating of an emergency PDU session, upon request of the upper layers to establish the emergency PDU session. The UE in non-3GPP access: a) shall initiate an initial registration procedure on the expiry of timers T3502, T3511 or T3346; b) may initiate an initial registration procedure for emergency services even if timers T3502, T3511 or T3346 are running; b1) may initiate an initial registration procedure even if timer T3502 or T3346 is running if the UE is a UE configured for high priority access in selected PLMN; c) shall initiate an initial registration procedure when entering a new PLMN or SNPN, except if timer T3346 is running and the new PLMN or SNPN is equivalent to the PLMN or SNPN where the UE started timer T3346; d) shall initiate an initial registration procedure if the 5GS update status is set to 5U2 NOT UPDATED, and timers T3511, T3502 and T3346 are not running; and e) may initiate an initial registration procedure with 5GS registration type IE set to "initial registration" for initiating of an emergency PDU session, upon request of the upper layers to establish the emergency PDU session.