Section: 5.17.3 Interworking with EPC in presence of Non-3GPP PDU Sessions
Content: When a UE is simultaneously connected to the 5GC over a 3GPP access and a non-3GPP access, it may have PDU Sessions associated with 3GPP access and PDU Sessions associated with non-3GPP access. When inter-system handover from 5GS to EPS is performed for PDU Sessions associated with 3GPP access, the PDU Sessions associated with non-3GPP access are kept anchored by the network in 5GC and the UE may either: - keep PDU Sessions associated with non-3GPP access in 5GS (5GC+N3IWF or TNGF) (i.e. the UE is then registered both in EPS and, for non-3GPP access, in 5GS); or - locally or explicitly release PDU Sessions associated with non-3GPP access; or - once in EPS, transfer PDU Sessions associated with non-3GPP access to E-UTRAN by triggering PDN connection establishment with Request Type "Handover", as specified in TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [26].