Section: 5.2.8.3.3 Nsmf_EventExposure_Subscribe service operation
Content: Service operation name: Nsmf_EventExposure_Subscribe. Description: This service operation is used by an NF to subscribe or modify a subscription for event notifications on a specified PDU Session or for all PDU Sessions of one UE, group of UE(s) or any UE. Input, Required: NF ID, Target of Event Reporting as defined in clause 5.2.8.3.1, (set of) Event ID(s) defined in clause 5.2.8.3.1, Notification Target Address (+ Notification Correlation ID), Event Reporting Information defined in Table 4.15.1-1. Input, Optional: Event Filter(s) associated with each Event ID; Event Filter(s) are defined in clause 5.2.8.3.1, Subscription Correlation ID (in the case of modification of the event subscription), Expiry time, DNN, S-NSSAI, DNAI, UPFId, UPF event exposure information (Type of measurement, granularity of measurement, reporting suggestion information, etc. associated with the UPF Event IDs as described in clause 4.15.4.5). NOTE: The SMF is generally meant to determine the UPF to contact for a subscription related to UPF event exposure. UPF ID is only provided to indicate a UP Path as defined in Table 6.4.1-1 of TS 23.288[ Architecture enhancements for 5G System (5GS) to support network data analytics services ]  [50], i.e. when the NWDAF has received the target UPF as part of statistics of observed service experience on an UP path involving that UPF. Output, Required: When the subscription is accepted: Subscription Correlation ID (required for management of this subscription), Expiry time (required if the subscription can be expired based on the operator's policy). Output, Optional: First corresponding event report is included, if available (see clause 4.15.1). Notification Target Address (+ Notification Correlation ID) is used to correlate Notifications sent by SMF or UPF with this subscription.