The present specification provides the stage 3 definition of the Network Data Analytics Function Services of the 5G System. The 5G System Architecture is defined in 3GPP TS 23.501 [2]. The stage 2 definition and related procedures for Network Data Analytics Function Services are specified in 3GPP TS 23.502 [3] and 3GPP TS 23.503 [4]. The 5G System stage 3 call flows are provided in 3GPP TS 29.513 [5]. The Technical Realization of the Service Based Architecture and the Principles and Guidelines for Services Definition are specified in 3GPP TS 29.500 [6] and 3GPP TS 29.501 [7]. The Network Data Analytics Function Services are provided by the Network Data Analytics Function (NWDAF). These services provide NWDAF slice congestion events notification and NWDAF operator specific analytics.