"The present specification provides the stage 3 definition of the Session Management Event Exposure Service (Nsmf_EventExposure) of the 5G System. The stage 2 definition and procedures of the Session Management Event Exposure Service are contained in 3GPP TS 23.502 [3] and 3GPP TS 23.503 [6]. The 5G System Architecture is defined in 3GPP TS 23.501 [2]. Stage 3 call flows for policy and charging control use cases are provided in 3GPP TS 29.513 [7]. The Technical Realization of the Service Based Architecture and the Principles and Guidelines for Services Definition of the 5G System are specified in 3GPP TS 29.500 [4] and 3GPP TS 29.501 [5]. The Session Management Event Exposure Service is provided by the Session Management Function (SMF). This service exposes events related to PDU Sessions observed at the SMF. [2] 3GPP TS 23.501: ""System Architecture for the 5G System; Stage 2"". [3] 3GPP TS 23.502: ""Procedures for the 5G System; Stage 2"". [4] 3GPP TS 29.500: ""5G System; Technical Realization of Service Based Architecture; Stage 3"". [5] 3GPP TS 29.501: ""5G System; Principles and Guidelines for Services Definition; Stage 3"". [6] 3GPP TS 23.503: ""Policy and Charging Control Framework for the 5G System; Stage 2"". [7] 3GPP TS 29.513: ""5G System; Policy and Charging Control signalling flows and QoS parameter mapping; Stage 3""."