Section: 4.15.3.2.13 Handling AF requests when the UE is identified via UE addressing information
Content: An AF may request, via the NEF, the Event Exposure (as defined in clause 4.15.3) or the parameter provisioning (as defined in clause 4.15.6) targeting an individual UE, identifying the target UE by providing UE addressing information. In this case the 5GC first needs to retrieve a UE Identifier based on: - the UE addressing information as provided by the AF: this may correspond to an UE IP address as allocated by 5GC or to a MAC address of the UE (when Ethernet PDU Sessions are targeted), - the corresponding DNN and/or S-NSSAI: this may have been provided by the AF or, alternatively, determined by the NEF using the identity of the AF. The NEF retrieves the UE Identifier by executing step 2 to 6 of the AF specific UE Identifier retrieval procedure described in clause 4.15.10. Once this is done, the 5GC may carry out the action requested by the AF and may deliver back to the AF an External Identifier representing an AF specific UE Identifier (as defined in TS 23.501[ System architecture for the 5G System (5GS) ]  [2]). This AF specific UE Identifier may later be used by the AF to issue further requests about the same UE. NOTE: The AF can use UE addressing information to identify the UE in a subscription request, but once received, this UE addressing information is translated into a GPSI and then the 5GC considers the subscription is associated with the GPSI and not with the UE address any more. The AF may have its own means to maintain the AF specific UE Identifier through, e.g. an AF session. After the retrieval of an AF specific UE Identifier the AF shall not keep maintaining a mapping between the returned AF specific UE Identifier and the UE IP address as this mapping may change.