Section: 8.7 Interworking without N26 interface in single-registration mode
Content: When the UE supports single-registration mode and network supports interworking procedure without N26 interface: - For mobility from 5GC to EPC, if the UE has a current EPS NAS security context, the UE shall start using the EPS security context as defined in TS 33.401[ 3GPP System Architecture Evolution (SAE); Security architecture ]  [10]. - For mobility from EPC to 5GC, if the UE has a current 5G NAS security context, the UE shall start using the 5G NAS security context as defined in the present document.